¿Cómo puedo exportar la matriz UIImage como una película?

Aquí está el último código de trabajo de iOS8 en Objective-C.

Tuvimos que hacer una variedad de ajustes a la respuesta de @Zoul anterior para que funcionara en la última versión de Xcode y iOS8. Aquí está nuestro código de trabajo completo que toma una matriz de UIImages, los convierte en a .archivo mov, lo guarda en un directorio temporal, luego lo mueve al rollo de cámara. Ensamblamos código de múltiples publicaciones diferentes para que esto funcione. Hemos resaltado las trampas que tuvimos que resolver para obtener el código trabajando en nuestros comentarios.

(1) Crear una colección de UIImages

[self saveMovieToLibrary]


- (IBAction)saveMovieToLibrary
{
    // You just need the height and width of the video here
    // For us, our input and output video was 640 height x 480 width
    // which is what we get from the iOS front camera
    ATHSingleton *singleton = [ATHSingleton singletons];
    int height = singleton.screenHeight;
    int width = singleton.screenWidth;

    // You can save a .mov or a .mp4 file        
    //NSString *fileNameOut = @"temp.mp4";
    NSString *fileNameOut = @"temp.mov";

    // We chose to save in the tmp/ directory on the device initially
    NSString *directoryOut = @"tmp/";
    NSString *outFile = [NSString stringWithFormat:@"%@%@",directoryOut,fileNameOut];
    NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:outFile]];
    NSURL *videoTempURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@%@", NSTemporaryDirectory(), fileNameOut]];

    // WARNING: AVAssetWriter does not overwrite files for us, so remove the destination file if it already exists
    NSFileManager *fileManager = [NSFileManager defaultManager];
    [fileManager removeItemAtPath:[videoTempURL path]  error:NULL];


    // Create your own array of UIImages        
    NSMutableArray *images = [NSMutableArray array];
    for (int i=0; i<singleton.numberOfScreenshots; i++)
    {
        // This was our routine that returned a UIImage. Just use your own.
        UIImage *image =[self uiimageFromCopyOfPixelBuffersUsingIndex:i];
        // We used a routine to write text onto every image 
        // so we could validate the images were actually being written when testing. This was it below. 
        image = [self writeToImage:image Text:[NSString stringWithFormat:@"%i",i ]];
        [images addObject:image];     
    }

// If you just want to manually add a few images - here is code you can uncomment
// NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/movie.mp4"]];
//    NSArray *images = [[NSArray alloc] initWithObjects:
//                      [UIImage imageNamed:@"add_ar.png"],
//                      [UIImage imageNamed:@"add_ja.png"],
//                      [UIImage imageNamed:@"add_ru.png"],
//                      [UIImage imageNamed:@"add_ru.png"],
//                      [UIImage imageNamed:@"add_ar.png"],
//                      [UIImage imageNamed:@"add_ja.png"],
//                      [UIImage imageNamed:@"add_ru.png"],
//                      [UIImage imageNamed:@"add_ar.png"],
//                      [UIImage imageNamed:@"add_en.png"], nil];



    [self writeImageAsMovie:images toPath:path size:CGSizeMake(height, width)];
}

Este es el método principal que crea su AssetWriter y le agrega imágenes para escribir.

(2) Conecta un AVAssetWriter

-(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size
{

    NSError *error = nil;

    // FIRST, start up an AVAssetWriter instance to write your video
    // Give it a destination path (for us: tmp/temp.mov)
    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:path]
                                                           fileType:AVFileTypeQuickTimeMovie
                                                              error:&error];


    NSParameterAssert(videoWriter);

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey,
                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey,
                                   nil];

    AVAssetWriterInput* writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
                                                                         outputSettings:videoSettings];

    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                                                                                     sourcePixelBufferAttributes:nil];
    NSParameterAssert(writerInput);
    NSParameterAssert([videoWriter canAddInput:writerInput]);
    [videoWriter addInput:writerInput];

(3) Iniciar una sesión de escritura (NOTA: el método continúa desde arriba)

    //Start a SESSION of writing. 
    // After you start a session, you will keep adding image frames 
    // until you are complete - then you will tell it you are done.
    [videoWriter startWriting];
    // This starts your video at time = 0
    [videoWriter startSessionAtSourceTime:kCMTimeZero];

    CVPixelBufferRef buffer = NULL;

    // This was just our utility class to get screen sizes etc.    
    ATHSingleton *singleton = [ATHSingleton singletons];

    int i = 0;
    while (1)
    {
        // Check if the writer is ready for more data, if not, just wait
        if(writerInput.readyForMoreMediaData){

            CMTime frameTime = CMTimeMake(150, 600);
            // CMTime = Value and Timescale.
            // Timescale = the number of tics per second you want
            // Value is the number of tics
            // For us - each frame we add will be 1/4th of a second
            // Apple recommend 600 tics per second for video because it is a 
            // multiple of the standard video rates 24, 30, 60 fps etc.
            CMTime lastTime=CMTimeMake(i*150, 600);
            CMTime presentTime=CMTimeAdd(lastTime, frameTime);

            if (i == 0) {presentTime = CMTimeMake(0, 600);} 
            // This ensures the first frame starts at 0.


            if (i >= [array count])
            {
                buffer = NULL;
            }
            else
            {
                // This command grabs the next UIImage and converts it to a CGImage
                buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
            }


            if (buffer)
            {
                // Give the CGImage to the AVAssetWriter to add to your video
                [adaptor appendPixelBuffer:buffer withPresentationTime:presentTime];
                i++;
            }
            else
            {

(4) Terminar la sesión (Nota: El método continúa desde arriba)

                //Finish the session:
                // This is important to be done exactly in this order
                [writerInput markAsFinished];
                // WARNING: finishWriting in the solution above is deprecated. 
                // You now need to give a completion handler.
                [videoWriter finishWritingWithCompletionHandler:^{
                    NSLog(@"Finished writing...checking completion status...");
                    if (videoWriter.status != AVAssetWriterStatusFailed && videoWriter.status == AVAssetWriterStatusCompleted)
                    {
                        NSLog(@"Video writing succeeded.");

                        // Move video to camera roll
                        // NOTE: You cannot write directly to the camera roll. 
                        // You must first write to an iOS directory then move it!
                        NSURL *videoTempURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@", path]];
                        [self saveToCameraRoll:videoTempURL];

                    } else
                    {
                        NSLog(@"Video writing failed: %@", videoWriter.error);
                    }

                }]; // end videoWriter finishWriting Block

                CVPixelBufferPoolRelease(adaptor.pixelBufferPool);

                NSLog (@"Done");
                break;
            }
        }
    }    
}

(5) Convierte tus UIImages a a CVPixelBufferRef
Este método le dará una referencia de búfer de píxel CV que es necesaria por el AssetWriter. Esto se obtiene de un CGImageRef que se obtiene de su UIImage (arriba).

- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
    // This again was just our utility class for the height & width of the
    // incoming video (640 height x 480 width)
    ATHSingleton *singleton = [ATHSingleton singletons];
    int height = singleton.screenHeight;
    int width = singleton.screenWidth;

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
                             nil];
    CVPixelBufferRef pxbuffer = NULL;

    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, width,
                                          height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
                                          &pxbuffer);

    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

    CVPixelBufferLockBaseAddress(pxbuffer, 0);
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
    NSParameterAssert(pxdata != NULL);

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef context = CGBitmapContextCreate(pxdata, width,
                                                 height, 8, 4*width, rgbColorSpace,
                                                 kCGImageAlphaNoneSkipFirst);
    NSParameterAssert(context);
    CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
                                           CGImageGetHeight(image)), image);
    CGColorSpaceRelease(rgbColorSpace);
    CGContextRelease(context);

    CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

    return pxbuffer;
}

(6) Mueva su Video al Rollo de Cámara Debido a que AVAssetWriter no puede escribir directamente en el rollo de cámara, esto mueve el video de "tmp/temp.mov " (o el nombre de archivo que hayas nombrado anteriormente) al rollo de cámara.

- (void) saveToCameraRoll:(NSURL *)srcURL
{
    NSLog(@"srcURL: %@", srcURL);

    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    ALAssetsLibraryWriteVideoCompletionBlock videoWriteCompletionBlock =
    ^(NSURL *newURL, NSError *error) {
        if (error) {
            NSLog( @"Error writing image with metadata to Photo Library: %@", error );
        } else {
            NSLog( @"Wrote image with metadata to Photo Library %@", newURL.absoluteString);
        }
    };

    if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:srcURL])
    {
        [library writeVideoAtPathToSavedPhotosAlbum:srcURL
                                    completionBlock:videoWriteCompletionBlock];
    }
}

La respuesta de Zoul arriba da un buen esquema de lo que lo estarás haciendo. Comentamos ampliamente este código para que pueda ver cómo se hizo usando código de trabajo.

NOTA: Esta es una solución Swift 2.1 (iOS8+, XCode 7.2) .

La semana pasada me propuse escribir el código de iOS para generar un video a partir de imágenes. Tenía un poco de experiencia en AVFoundation, pero nunca había oído hablar de un CVPixelBuffer. Me encontré con las respuestas en esta página y también aquí. Me tomó varios días diseccionar todo y volver a juntarlo todo en Swift de una manera que tuviera sentido para mi cerebro. A continuación está lo que se me ocurrió.

NOTA: Si copie / pegue todo el código a continuación en un solo archivo Swift, que debe compilar. Solo tendrá que ajustar loadImages() y los valores RenderSettings.

Parte 1: Configurar las cosas

Aquí grupo todas las configuraciones relacionadas con la exportación en una sola estructura RenderSettings.

import AVFoundation
import UIKit
import Photos

struct RenderSettings {

    var width: CGFloat = 1280
    var height: CGFloat = 720
    var fps: Int32 = 2   // 2 frames per second
    var avCodecKey = AVVideoCodecH264
    var videoFilename = "render"
    var videoFilenameExt = "mp4"

    var size: CGSize {
        return CGSize(width: width, height: height)
    }

    var outputURL: NSURL {
        // Use the CachesDirectory so the rendered video file sticks around as long as we need it to.
        // Using the CachesDirectory ensures the file won't be included in a backup of the app.
        let fileManager = NSFileManager.defaultManager()
        if let tmpDirURL = try? fileManager.URLForDirectory(.CachesDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true) {
            return tmpDirURL.URLByAppendingPathComponent(videoFilename).URLByAppendingPathExtension(videoFilenameExt)
        }
        fatalError("URLForDirectory() failed")
    }
}

Parte 2: El ImageAlimator

La clase ImageAnimator conoce tus imágenes y usa la clase VideoWriter para realizar el renderizado. La idea es mantener el código de contenido de video separado del código de AVFoundation de bajo nivel. Me también se agregó saveToLibrary() aquí como una función de clase que se llama al final de la cadena para guardar el video en la Biblioteca de fotos.

class ImageAnimator {

    // Apple suggests a timescale of 600 because it's a multiple of standard video rates 24, 25, 30, 60 fps etc.
    static let kTimescale: Int32 = 600

    let settings: RenderSettings
    let videoWriter: VideoWriter
    var images: [UIImage]!

    var frameNum = 0

    class func saveToLibrary(videoURL: NSURL) {
        PHPhotoLibrary.requestAuthorization { status in
            guard status == .Authorized else { return }

            PHPhotoLibrary.sharedPhotoLibrary().performChanges({
                PHAssetChangeRequest.creationRequestForAssetFromVideoAtFileURL(videoURL)
                }) { success, error in
                    if !success {
                        print("Could not save video to photo library:", error)
                    }
            }
        }
    }

    class func removeFileAtURL(fileURL: NSURL) {
        do {
            try NSFileManager.defaultManager().removeItemAtPath(fileURL.path!)
        }
        catch _ as NSError {
            // Assume file doesn't exist.
        }
    }

    init(renderSettings: RenderSettings) {
        settings = renderSettings
        videoWriter = VideoWriter(renderSettings: settings)
        images = loadImages()
    }

    func render(completion: ()->Void) {

        // The VideoWriter will fail if a file exists at the URL, so clear it out first.
        ImageAnimator.removeFileAtURL(settings.outputURL)

        videoWriter.start()
        videoWriter.render(appendPixelBuffers) {
            ImageAnimator.saveToLibrary(self.settings.outputURL)
            completion()
        }

    }

    // Replace this logic with your own.
    func loadImages() -> [UIImage] {
        var images = [UIImage]()
        for index in 1...10 {
            let filename = "\(index).jpg"
            images.append(UIImage(named: filename)!)
        }
        return images
    }

    // This is the callback function for VideoWriter.render()
    func appendPixelBuffers(writer: VideoWriter) -> Bool {

        let frameDuration = CMTimeMake(Int64(ImageAnimator.kTimescale / settings.fps), ImageAnimator.kTimescale)

        while !images.isEmpty {

            if writer.isReadyForData == false {
                // Inform writer we have more buffers to write.
                return false
            }

            let image = images.removeFirst()
            let presentationTime = CMTimeMultiply(frameDuration, Int32(frameNum))
            let success = videoWriter.addImage(image, withPresentationTime: presentationTime)
            if success == false {
                fatalError("addImage() failed")
            }

            frameNum++
        }

        // Inform writer all buffers have been written.
        return true
    }

}

Parte 3: El VideoWriter

La clase VideoWriter hace todo el levantamiento pesado de AVFoundation. Es sobre todo una envoltura alrededor de AVAssetWriter y AVAssetWriterInput. También contiene código de fantasía escrito por not me que sabe cómo traducir una imagen en un CVPixelBuffer.

class VideoWriter {

    let renderSettings: RenderSettings

    var videoWriter: AVAssetWriter!
    var videoWriterInput: AVAssetWriterInput!
    var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!

    var isReadyForData: Bool {
        return videoWriterInput?.readyForMoreMediaData ?? false
    }

    class func pixelBufferFromImage(image: UIImage, pixelBufferPool: CVPixelBufferPool, size: CGSize) -> CVPixelBuffer {

        var pixelBufferOut: CVPixelBuffer?

        let status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
        if status != kCVReturnSuccess {
            fatalError("CVPixelBufferPoolCreatePixelBuffer() failed")
        }

        let pixelBuffer = pixelBufferOut!

        CVPixelBufferLockBaseAddress(pixelBuffer, 0)

        let data = CVPixelBufferGetBaseAddress(pixelBuffer)
        let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
        let context = CGBitmapContextCreate(data, Int(size.width), Int(size.height),
            8, CVPixelBufferGetBytesPerRow(pixelBuffer), rgbColorSpace, CGImageAlphaInfo.PremultipliedFirst.rawValue)

        CGContextClearRect(context, CGRectMake(0, 0, size.width, size.height))

        let horizontalRatio = size.width / image.size.width
        let verticalRatio = size.height / image.size.height
        //aspectRatio = max(horizontalRatio, verticalRatio) // ScaleAspectFill
        let aspectRatio = min(horizontalRatio, verticalRatio) // ScaleAspectFit

        let newSize = CGSize(width: image.size.width * aspectRatio, height: image.size.height * aspectRatio)

        let x = newSize.width < size.width ? (size.width - newSize.width) / 2 : 0
        let y = newSize.height < size.height ? (size.height - newSize.height) / 2 : 0

        CGContextDrawImage(context, CGRectMake(x, y, newSize.width, newSize.height), image.CGImage)
        CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)

        return pixelBuffer
    }

    init(renderSettings: RenderSettings) {
        self.renderSettings = renderSettings
    }

    func start() {

        let avOutputSettings: [String: AnyObject] = [
            AVVideoCodecKey: renderSettings.avCodecKey,
            AVVideoWidthKey: NSNumber(float: Float(renderSettings.width)),
            AVVideoHeightKey: NSNumber(float: Float(renderSettings.height))
        ]

        func createPixelBufferAdaptor() {
            let sourcePixelBufferAttributesDictionary = [
                kCVPixelBufferPixelFormatTypeKey as String: NSNumber(unsignedInt: kCVPixelFormatType_32ARGB),
                kCVPixelBufferWidthKey as String: NSNumber(float: Float(renderSettings.width)),
                kCVPixelBufferHeightKey as String: NSNumber(float: Float(renderSettings.height))
            ]
            pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
                sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
        }

        func createAssetWriter(outputURL: NSURL) -> AVAssetWriter {
            guard let assetWriter = try? AVAssetWriter(URL: outputURL, fileType: AVFileTypeMPEG4) else {
                fatalError("AVAssetWriter() failed")
            }

            guard assetWriter.canApplyOutputSettings(avOutputSettings, forMediaType: AVMediaTypeVideo) else {
                fatalError("canApplyOutputSettings() failed")
            }

            return assetWriter
        }

        videoWriter = createAssetWriter(renderSettings.outputURL)
        videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: avOutputSettings)

        if videoWriter.canAddInput(videoWriterInput) {
            videoWriter.addInput(videoWriterInput)
        }
        else {
            fatalError("canAddInput() returned false")
        }

        // The pixel buffer adaptor must be created before we start writing.
        createPixelBufferAdaptor()

        if videoWriter.startWriting() == false {
            fatalError("startWriting() failed")
        }

        videoWriter.startSessionAtSourceTime(kCMTimeZero)

        precondition(pixelBufferAdaptor.pixelBufferPool != nil, "nil pixelBufferPool")
    }

    func render(appendPixelBuffers: (VideoWriter)->Bool, completion: ()->Void) {

        precondition(videoWriter != nil, "Call start() to initialze the writer")

        let queue = dispatch_queue_create("mediaInputQueue", nil)
        videoWriterInput.requestMediaDataWhenReadyOnQueue(queue) {
            let isFinished = appendPixelBuffers(self)
            if isFinished {
                self.videoWriterInput.markAsFinished()
                self.videoWriter.finishWritingWithCompletionHandler() {
                    dispatch_async(dispatch_get_main_queue()) {
                        completion()
                    }
                }
            }
            else {
                // Fall through. The closure will be called again when the writer is ready.
            }
        }
    }

    func addImage(image: UIImage, withPresentationTime presentationTime: CMTime) -> Bool {

        precondition(pixelBufferAdaptor != nil, "Call start() to initialze the writer")

        let pixelBuffer = VideoWriter.pixelBufferFromImage(image, pixelBufferPool: pixelBufferAdaptor.pixelBufferPool!, size: renderSettings.size)
        return pixelBufferAdaptor.appendPixelBuffer(pixelBuffer, withPresentationTime: presentationTime)
    }

}

Parte 4: Hacer que suceda

Una vez que todo está en su lugar, estos son sus 3 magia líneas:

let settings = RenderSettings()
let imageAnimator = ImageAnimator(renderSettings: settings)
imageAnimator.render() {
    print("yes")
}

Tomé las ideas principales de Zoul e incorporé el método AVAssetWriterInputPixelBufferAdaptor e hice los inicios de un pequeño framework.

Siéntase libre de comprobarlo y mejorarlo! CEMovieMaker

Aquí hay un Swift 2.versión x probada en iOS 8. Combina respuestas de @ Scott Raposa y @Praxiteles junto con código de @acj contribuido para otra pregunta. El código de @acj está aquí: https://gist.github.com/acj/6ae90aa1ebb8cad6b47b . @TimBull también proporcionó código.

Al igual que @Scott Raposa, nunca había oído hablar de CVPixelBufferPoolCreatePixelBuffer y de varias otras funciones, y mucho menos había entendido cómo usarlas.

Lo que ves a continuación fue improvisado en su mayoría por ensayo y error y de leer los documentos de Apple. Por favor, utilícelo con precaución y proporcione sugerencias si hay errores.

Uso:

import UIKit
import AVFoundation
import Photos

writeImagesAsMovie(yourImages, videoPath: yourPath, videoSize: yourSize, videoFPS: 30)

Código:

func writeImagesAsMovie(allImages: [UIImage], videoPath: String, videoSize: CGSize, videoFPS: Int32) {
    // Create AVAssetWriter to write video
    guard let assetWriter = createAssetWriter(videoPath, size: videoSize) else {
        print("Error converting images to video: AVAssetWriter not created")
        return
    }

    // If here, AVAssetWriter exists so create AVAssetWriterInputPixelBufferAdaptor
    let writerInput = assetWriter.inputs.filter{ $0.mediaType == AVMediaTypeVideo }.first!
    let sourceBufferAttributes : [String : AnyObject] = [
        kCVPixelBufferPixelFormatTypeKey as String : Int(kCVPixelFormatType_32ARGB),
        kCVPixelBufferWidthKey as String : videoSize.width,
        kCVPixelBufferHeightKey as String : videoSize.height,
        ]
    let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: writerInput, sourcePixelBufferAttributes: sourceBufferAttributes)

    // Start writing session
    assetWriter.startWriting()
    assetWriter.startSessionAtSourceTime(kCMTimeZero)
    if (pixelBufferAdaptor.pixelBufferPool == nil) {
        print("Error converting images to video: pixelBufferPool nil after starting session")
        return
    }

    // -- Create queue for <requestMediaDataWhenReadyOnQueue>
    let mediaQueue = dispatch_queue_create("mediaInputQueue", nil)

    // -- Set video parameters
    let frameDuration = CMTimeMake(1, videoFPS)
    var frameCount = 0

    // -- Add images to video
    let numImages = allImages.count
    writerInput.requestMediaDataWhenReadyOnQueue(mediaQueue, usingBlock: { () -> Void in
        // Append unadded images to video but only while input ready
        while (writerInput.readyForMoreMediaData && frameCount < numImages) {
            let lastFrameTime = CMTimeMake(Int64(frameCount), videoFPS)
            let presentationTime = frameCount == 0 ? lastFrameTime : CMTimeAdd(lastFrameTime, frameDuration)

            if !self.appendPixelBufferForImageAtURL(allImages[frameCount], pixelBufferAdaptor: pixelBufferAdaptor, presentationTime: presentationTime) {
                print("Error converting images to video: AVAssetWriterInputPixelBufferAdapter failed to append pixel buffer")
                return
            }

            frameCount += 1
        }

        // No more images to add? End video.
        if (frameCount >= numImages) {
            writerInput.markAsFinished()
            assetWriter.finishWritingWithCompletionHandler {
                if (assetWriter.error != nil) {
                    print("Error converting images to video: \(assetWriter.error)")
                } else {
                    self.saveVideoToLibrary(NSURL(fileURLWithPath: videoPath))
                    print("Converted images to movie @ \(videoPath)")
                }
            }
        }
    })
}


func createAssetWriter(path: String, size: CGSize) -> AVAssetWriter? {
    // Convert <path> to NSURL object
    let pathURL = NSURL(fileURLWithPath: path)

    // Return new asset writer or nil
    do {
        // Create asset writer
        let newWriter = try AVAssetWriter(URL: pathURL, fileType: AVFileTypeMPEG4)

        // Define settings for video input
        let videoSettings: [String : AnyObject] = [
            AVVideoCodecKey  : AVVideoCodecH264,
            AVVideoWidthKey  : size.width,
            AVVideoHeightKey : size.height,
            ]

        // Add video input to writer
        let assetWriterVideoInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
        newWriter.addInput(assetWriterVideoInput)

        // Return writer
        print("Created asset writer for \(size.width)x\(size.height) video")
        return newWriter
    } catch {
        print("Error creating asset writer: \(error)")
        return nil
    }
}


func appendPixelBufferForImageAtURL(image: UIImage, pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor, presentationTime: CMTime) -> Bool {
    var appendSucceeded = false

    autoreleasepool {
        if  let pixelBufferPool = pixelBufferAdaptor.pixelBufferPool {
            let pixelBufferPointer = UnsafeMutablePointer<CVPixelBuffer?>.alloc(1)
            let status: CVReturn = CVPixelBufferPoolCreatePixelBuffer(
                kCFAllocatorDefault,
                pixelBufferPool,
                pixelBufferPointer
            )

            if let pixelBuffer = pixelBufferPointer.memory where status == 0 {
                fillPixelBufferFromImage(image, pixelBuffer: pixelBuffer)
                appendSucceeded = pixelBufferAdaptor.appendPixelBuffer(pixelBuffer, withPresentationTime: presentationTime)
                pixelBufferPointer.destroy()
            } else {
                NSLog("Error: Failed to allocate pixel buffer from pool")
            }

            pixelBufferPointer.dealloc(1)
        }
    }

    return appendSucceeded
}


func fillPixelBufferFromImage(image: UIImage, pixelBuffer: CVPixelBufferRef) {
    CVPixelBufferLockBaseAddress(pixelBuffer, 0)

    let pixelData = CVPixelBufferGetBaseAddress(pixelBuffer)
    let rgbColorSpace = CGColorSpaceCreateDeviceRGB()

    // Create CGBitmapContext
    let context = CGBitmapContextCreate(
        pixelData,
        Int(image.size.width),
        Int(image.size.height),
        8,
        CVPixelBufferGetBytesPerRow(pixelBuffer),
        rgbColorSpace,
        CGImageAlphaInfo.PremultipliedFirst.rawValue
    )

    // Draw image into context
    CGContextDrawImage(context, CGRectMake(0, 0, image.size.width, image.size.height), image.CGImage)

    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)
}


func saveVideoToLibrary(videoURL: NSURL) {
    PHPhotoLibrary.requestAuthorization { status in
        // Return if unauthorized
        guard status == .Authorized else {
            print("Error saving video: unauthorized access")
            return
        }

        // If here, save video to library
        PHPhotoLibrary.sharedPhotoLibrary().performChanges({
            PHAssetChangeRequest.creationRequestForAssetFromVideoAtFileURL(videoURL)
        }) { success, error in
            if !success {
                print("Error saving video: \(error)")
            }
        }
    }
}

Aquí está la versión swift3 cómo convertir la matriz de imágenes al video

import Foundation
import AVFoundation
import UIKit

typealias CXEMovieMakerCompletion = (URL) -> Void
typealias CXEMovieMakerUIImageExtractor = (AnyObject) -> UIImage?


public class ImagesToVideoUtils: NSObject {

    static let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    static let tempPath = paths[0] + "/exprotvideo.mp4"
    static let fileURL = URL(fileURLWithPath: tempPath)
//    static let tempPath = NSTemporaryDirectory() + "/exprotvideo.mp4"
//    static let fileURL = URL(fileURLWithPath: tempPath)


    var assetWriter:AVAssetWriter!
    var writeInput:AVAssetWriterInput!
    var bufferAdapter:AVAssetWriterInputPixelBufferAdaptor!
    var videoSettings:[String : Any]!
    var frameTime:CMTime!
    //var fileURL:URL!

    var completionBlock: CXEMovieMakerCompletion?
    var movieMakerUIImageExtractor:CXEMovieMakerUIImageExtractor?


    public class func videoSettings(codec:String, width:Int, height:Int) -> [String: Any]{
        if(Int(width) % 16 != 0){
            print("warning: video settings width must be divisible by 16")
        }

        let videoSettings:[String: Any] = [AVVideoCodecKey: AVVideoCodecJPEG, //AVVideoCodecH264,
                                           AVVideoWidthKey: width,
                                           AVVideoHeightKey: height]

        return videoSettings
    }

    public init(videoSettings: [String: Any]) {
        super.init()


        if(FileManager.default.fileExists(atPath: ImagesToVideoUtils.tempPath)){
            guard (try? FileManager.default.removeItem(atPath: ImagesToVideoUtils.tempPath)) != nil else {
                print("remove path failed")
                return
            }
        }


        self.assetWriter = try! AVAssetWriter(url: ImagesToVideoUtils.fileURL, fileType: AVFileTypeQuickTimeMovie)

        self.videoSettings = videoSettings
        self.writeInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: videoSettings)
        assert(self.assetWriter.canAdd(self.writeInput), "add failed")

        self.assetWriter.add(self.writeInput)
        let bufferAttributes:[String: Any] = [kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32ARGB)]
        self.bufferAdapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: self.writeInput, sourcePixelBufferAttributes: bufferAttributes)
        self.frameTime = CMTimeMake(1, 5)
    }

    func createMovieFrom(urls: [URL], withCompletion: @escaping CXEMovieMakerCompletion){
        self.createMovieFromSource(images: urls as [AnyObject], extractor:{(inputObject:AnyObject) ->UIImage? in
            return UIImage(data: try! Data(contentsOf: inputObject as! URL))}, withCompletion: withCompletion)
    }

    func createMovieFrom(images: [UIImage], withCompletion: @escaping CXEMovieMakerCompletion){
        self.createMovieFromSource(images: images, extractor: {(inputObject:AnyObject) -> UIImage? in
            return inputObject as? UIImage}, withCompletion: withCompletion)
    }

    func createMovieFromSource(images: [AnyObject], extractor: @escaping CXEMovieMakerUIImageExtractor, withCompletion: @escaping CXEMovieMakerCompletion){
        self.completionBlock = withCompletion

        self.assetWriter.startWriting()
        self.assetWriter.startSession(atSourceTime: kCMTimeZero)

        let mediaInputQueue = DispatchQueue(label: "mediaInputQueue")
        var i = 0
        let frameNumber = images.count

        self.writeInput.requestMediaDataWhenReady(on: mediaInputQueue){
            while(true){
                if(i >= frameNumber){
                    break
                }

                if (self.writeInput.isReadyForMoreMediaData){
                    var sampleBuffer:CVPixelBuffer?
                    autoreleasepool{
                        let img = extractor(images[i])
                        if img == nil{
                            i += 1
                            print("Warning: counld not extract one of the frames")
                            //continue
                        }
                        sampleBuffer = self.newPixelBufferFrom(cgImage: img!.cgImage!)
                    }
                    if (sampleBuffer != nil){
                        if(i == 0){
                            self.bufferAdapter.append(sampleBuffer!, withPresentationTime: kCMTimeZero)
                        }else{
                            let value = i - 1
                            let lastTime = CMTimeMake(Int64(value), self.frameTime.timescale)
                            let presentTime = CMTimeAdd(lastTime, self.frameTime)
                            self.bufferAdapter.append(sampleBuffer!, withPresentationTime: presentTime)
                        }
                        i = i + 1
                    }
                }
            }
            self.writeInput.markAsFinished()
            self.assetWriter.finishWriting {
                DispatchQueue.main.sync {
                    self.completionBlock!(ImagesToVideoUtils.fileURL)
                }
            }
        }
    }

    func newPixelBufferFrom(cgImage:CGImage) -> CVPixelBuffer?{
        let options:[String: Any] = [kCVPixelBufferCGImageCompatibilityKey as String: true, kCVPixelBufferCGBitmapContextCompatibilityKey as String: true]
        var pxbuffer:CVPixelBuffer?
        let frameWidth = self.videoSettings[AVVideoWidthKey] as! Int
        let frameHeight = self.videoSettings[AVVideoHeightKey] as! Int

        let status = CVPixelBufferCreate(kCFAllocatorDefault, frameWidth, frameHeight, kCVPixelFormatType_32ARGB, options as CFDictionary?, &pxbuffer)
        assert(status == kCVReturnSuccess && pxbuffer != nil, "newPixelBuffer failed")

        CVPixelBufferLockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))
        let pxdata = CVPixelBufferGetBaseAddress(pxbuffer!)
        let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
        let context = CGContext(data: pxdata, width: frameWidth, height: frameHeight, bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pxbuffer!), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)
        assert(context != nil, "context is nil")

        context!.concatenate(CGAffineTransform.identity)
        context!.draw(cgImage, in: CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height))
        CVPixelBufferUnlockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))
        return pxbuffer
    }
}

Lo uso junto con la captura de pantalla, básicamente para crear un video de captura de pantalla, aquí está la historia completa/ejemplo completo.

Acabo de traducir la respuesta de @Scott Raposa a swift3 (con algunos cambios muy pequeños):

import AVFoundation
import UIKit
import Photos

struct RenderSettings {

    var size : CGSize = .zero
    var fps: Int32 = 6   // frames per second
    var avCodecKey = AVVideoCodecH264
    var videoFilename = "render"
    var videoFilenameExt = "mp4"


    var outputURL: URL {
        // Use the CachesDirectory so the rendered video file sticks around as long as we need it to.
        // Using the CachesDirectory ensures the file won't be included in a backup of the app.
        let fileManager = FileManager.default
        if let tmpDirURL = try? fileManager.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: true) {
            return tmpDirURL.appendingPathComponent(videoFilename).appendingPathExtension(videoFilenameExt)
        }
        fatalError("URLForDirectory() failed")
    }
}


class ImageAnimator {

    // Apple suggests a timescale of 600 because it's a multiple of standard video rates 24, 25, 30, 60 fps etc.
    static let kTimescale: Int32 = 600

    let settings: RenderSettings
    let videoWriter: VideoWriter
    var images: [UIImage]!

    var frameNum = 0

    class func saveToLibrary(videoURL: URL) {
        PHPhotoLibrary.requestAuthorization { status in
            guard status == .authorized else { return }

            PHPhotoLibrary.shared().performChanges({
                PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: videoURL)
            }) { success, error in
                if !success {
                    print("Could not save video to photo library:", error)
                }
            }
        }
    }

    class func removeFileAtURL(fileURL: URL) {
        do {
            try FileManager.default.removeItem(atPath: fileURL.path)
        }
        catch _ as NSError {
            // Assume file doesn't exist.
        }
    }

    init(renderSettings: RenderSettings) {
        settings = renderSettings
        videoWriter = VideoWriter(renderSettings: settings)
//        images = loadImages()
    }

    func render(completion: (()->Void)?) {

        // The VideoWriter will fail if a file exists at the URL, so clear it out first.
        ImageAnimator.removeFileAtURL(fileURL: settings.outputURL)

        videoWriter.start()
        videoWriter.render(appendPixelBuffers: appendPixelBuffers) {
            ImageAnimator.saveToLibrary(videoURL: self.settings.outputURL)
            completion?()
        }

    }

//    // Replace this logic with your own.
//    func loadImages() -> [UIImage] {
//        var images = [UIImage]()
//        for index in 1...10 {
//            let filename = "\(index).jpg"
//            images.append(UIImage(named: filename)!)
//        }
//        return images
//    }

    // This is the callback function for VideoWriter.render()
    func appendPixelBuffers(writer: VideoWriter) -> Bool {

        let frameDuration = CMTimeMake(Int64(ImageAnimator.kTimescale / settings.fps), ImageAnimator.kTimescale)

        while !images.isEmpty {

            if writer.isReadyForData == false {
                // Inform writer we have more buffers to write.
                return false
            }

            let image = images.removeFirst()
            let presentationTime = CMTimeMultiply(frameDuration, Int32(frameNum))
            let success = videoWriter.addImage(image: image, withPresentationTime: presentationTime)
            if success == false {
                fatalError("addImage() failed")
            }

            frameNum += 1
        }

        // Inform writer all buffers have been written.
        return true
    }

}


class VideoWriter {

    let renderSettings: RenderSettings

    var videoWriter: AVAssetWriter!
    var videoWriterInput: AVAssetWriterInput!
    var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!

    var isReadyForData: Bool {
        return videoWriterInput?.isReadyForMoreMediaData ?? false
    }

    class func pixelBufferFromImage(image: UIImage, pixelBufferPool: CVPixelBufferPool, size: CGSize) -> CVPixelBuffer {

        var pixelBufferOut: CVPixelBuffer?

        let status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
        if status != kCVReturnSuccess {
            fatalError("CVPixelBufferPoolCreatePixelBuffer() failed")
        }

        let pixelBuffer = pixelBufferOut!

        CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))

        let data = CVPixelBufferGetBaseAddress(pixelBuffer)
        let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
        let context = CGContext(data: data, width: Int(size.width), height: Int(size.height),
                                bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue)

        context!.clear(CGRect(x:0,y: 0,width: size.width,height: size.height))

        let horizontalRatio = size.width / image.size.width
        let verticalRatio = size.height / image.size.height
        //aspectRatio = max(horizontalRatio, verticalRatio) // ScaleAspectFill
        let aspectRatio = min(horizontalRatio, verticalRatio) // ScaleAspectFit

        let newSize = CGSize(width: image.size.width * aspectRatio, height: image.size.height * aspectRatio)

        let x = newSize.width < size.width ? (size.width - newSize.width) / 2 : 0
        let y = newSize.height < size.height ? (size.height - newSize.height) / 2 : 0

        context?.draw(image.cgImage!, in: CGRect(x:x,y: y, width: newSize.width, height: newSize.height))
        CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))

        return pixelBuffer
    }

    init(renderSettings: RenderSettings) {
        self.renderSettings = renderSettings
    }

    func start() {

        let avOutputSettings: [String: Any] = [
            AVVideoCodecKey: renderSettings.avCodecKey,
            AVVideoWidthKey: NSNumber(value: Float(renderSettings.size.width)),
            AVVideoHeightKey: NSNumber(value: Float(renderSettings.size.height))
        ]

        func createPixelBufferAdaptor() {
            let sourcePixelBufferAttributesDictionary = [
                kCVPixelBufferPixelFormatTypeKey as String: NSNumber(value: kCVPixelFormatType_32ARGB),
                kCVPixelBufferWidthKey as String: NSNumber(value: Float(renderSettings.size.width)),
                kCVPixelBufferHeightKey as String: NSNumber(value: Float(renderSettings.size.height))
            ]
            pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput,
                                                                      sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
        }

        func createAssetWriter(outputURL: URL) -> AVAssetWriter {
            guard let assetWriter = try? AVAssetWriter(outputURL: outputURL, fileType: AVFileTypeMPEG4) else {
                fatalError("AVAssetWriter() failed")
            }

            guard assetWriter.canApply(outputSettings: avOutputSettings, forMediaType: AVMediaTypeVideo) else {
                fatalError("canApplyOutputSettings() failed")
            }

            return assetWriter
        }

        videoWriter = createAssetWriter(outputURL: renderSettings.outputURL)
        videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: avOutputSettings)

        if videoWriter.canAdd(videoWriterInput) {
            videoWriter.add(videoWriterInput)
        }
        else {
            fatalError("canAddInput() returned false")
        }

        // The pixel buffer adaptor must be created before we start writing.
        createPixelBufferAdaptor()

        if videoWriter.startWriting() == false {
            fatalError("startWriting() failed")
        }

        videoWriter.startSession(atSourceTime: kCMTimeZero)

        precondition(pixelBufferAdaptor.pixelBufferPool != nil, "nil pixelBufferPool")
    }

    func render(appendPixelBuffers: ((VideoWriter)->Bool)?, completion: (()->Void)?) {

        precondition(videoWriter != nil, "Call start() to initialze the writer")

        let queue = DispatchQueue(label: "mediaInputQueue")
        videoWriterInput.requestMediaDataWhenReady(on: queue) {
            let isFinished = appendPixelBuffers?(self) ?? false
            if isFinished {
                self.videoWriterInput.markAsFinished()
                self.videoWriter.finishWriting() {
                    DispatchQueue.main.async {
                        completion?()
                    }
                }
            }
            else {
                // Fall through. The closure will be called again when the writer is ready.
            }
        }
    }

    func addImage(image: UIImage, withPresentationTime presentationTime: CMTime) -> Bool {

        precondition(pixelBufferAdaptor != nil, "Call start() to initialze the writer")

        let pixelBuffer = VideoWriter.pixelBufferFromImage(image: image, pixelBufferPool: pixelBufferAdaptor.pixelBufferPool!, size: renderSettings.size)
        return pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: presentationTime)
    }

}

Versión Swift 4 para macOS (no iOS), basada en @Mikita Manko.

import AVFoundation
import AppKit

class VidWriter {

    var assetWriter: AVAssetWriter
    var writerInput: AVAssetWriterInput
    var bufferAdapter: AVAssetWriterInputPixelBufferAdaptor!
    var videoSettings: [String : Any]
    var frameTime: CMTime!
    var fileUrl: URL!

    init(url: URL, vidSettings: [String : Any]) {
        self.assetWriter = try! AVAssetWriter(url: url, fileType: AVFileType.mov)
        self.fileUrl = url
        self.videoSettings = vidSettings
        self.writerInput = AVAssetWriterInput(mediaType: AVMediaType.video, outputSettings: self.videoSettings)

        assert(self.assetWriter.canAdd(self.writerInput), "Writer cannot add input")

        self.assetWriter.add(self.writerInput)

        let bufferAttributes = [kCVPixelBufferPixelFormatTypeKey as String : Int(kCVPixelFormatType_32ARGB)]
        self.bufferAdapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: self.writerInput, sourcePixelBufferAttributes: bufferAttributes)
        self.frameTime = CMTimeMake(1, 5) // Default value, use 'applyTimeWith(duration:)' to apply specific time.
    }

    static func videoSettings(codec: String = AVVideoCodecJPEG, width: Int, height: Int) -> [String : Any] {

        // AVVideoCodecJPEG also works, but result in a much bigger file.
        return [
            AVVideoCodecKey : AVVideoCodecH264, //AVVideoCodecJPEG,
            AVVideoWidthKey : width,
            AVVideoHeightKey : height
        ]
    }

    /**
    Update the movie time with the number of images and the duration per image.

    - Parameter duration: The duration per frame (image)
    - Parameter frameNumber: The number of frames (images)
    */
    func applyTimeWith(duration: Float, frameNumber: Int) {

        let scale = Float(frameNumber) / (Float(frameNumber) * duration)

        self.frameTime = CMTimeMake(1, Int32(scale))
    }

    func createMovieFrom(images: [NSImage], completion: @escaping (URL) -> Void) {

        self.assetWriter.startWriting()
        self.assetWriter.startSession(atSourceTime: kCMTimeZero)

        let mediaInputQueue = DispatchQueue(label: "MediaInputQueu")

        var i = 0
        let frameNumber = images.count

        self.writerInput.requestMediaDataWhenReady(on: mediaInputQueue) {

            while i < frameNumber {
                if self.writerInput.isReadyForMoreMediaData {

                    var sampleBuffer: CVPixelBuffer?

                    autoreleasepool(invoking: {

                        let img = images[i]

                        var imgRect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)
                        sampleBuffer = self.newPixelBufferFrom(cgImage: img.cgImage(forProposedRect: &imgRect, context: nil, hints: nil)!)

                    }) // End of autoreleasepool

                    if sampleBuffer != nil {
                        if i == 0 {
                            self.bufferAdapter.append(sampleBuffer!, withPresentationTime: kCMTimeZero)
                        }
                        else {
                            let value = i - 1
                            let lastTime = CMTimeMake(Int64(value), self.frameTime.timescale)
                            let presentTime = CMTimeAdd(lastTime, self.frameTime)

                            self.bufferAdapter.append(sampleBuffer!, withPresentationTime: presentTime)

                        }

                        i += 1
                    }

                } // End of isReadyForMoreMediaData

            } // End of while loop

            self.writerInput.markAsFinished()
            self.assetWriter.finishWriting {
                DispatchQueue.main.async {
                    // At this point, the given URL will already have the ready file.
                    // You can just use the URL passed in the init.
                    completion(self.fileUrl)
                }
            }
        }
    }

    func newPixelBufferFrom(cgImage: CGImage) -> CVPixelBuffer? {

        let options: [String : Any] = [kCVPixelBufferCGImageCompatibilityKey as String : true, kCVPixelBufferCGBitmapContextCompatibilityKey as String : true]

        var pxbuffer: CVPixelBuffer?

        let frameWidth = self.videoSettings[AVVideoWidthKey] as! Int
        let frameHeight = self.videoSettings[AVVideoHeightKey] as! Int

        let status = CVPixelBufferCreate(kCFAllocatorDefault, frameWidth, frameHeight, kCVPixelFormatType_32ARGB, options as CFDictionary?, &pxbuffer)

        assert(status == kCVReturnSuccess && pxbuffer != nil, "newPixelBuffer failed")
        CVPixelBufferLockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))
        let pxData = CVPixelBufferGetBaseAddress(pxbuffer!)
        let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
        let context = CGContext(data: pxData, width: frameWidth, height: frameHeight, bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pxbuffer!), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)

        assert(context != nil, "context is nil")

        context!.concatenate(CGAffineTransform.identity)
        context!.draw(cgImage, in: CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height))
        CVPixelBufferUnlockBaseAddress(pxbuffer!, CVPixelBufferLockFlags(rawValue: 0))

        return pxbuffer
    }
}

Uso:

let settings = VidWriter.videoSettings(width: cgImg.width, height: cgImg.height)

// Note: There should be no file at the targetUrl or nothing will be written.
self.vidWriter = VidWriter(url: targetUrl!, vidSettings: settings)
self.vidWriter.applyTimeWith(duration: durationPerFrame, frameNumber: images.count)

self.vidWriter.createMovieFrom(images: images, completion: { (finalUrl) in
    print("Completed")
})

Bueno, esto es un poco difícil de implementar en pure Objective-C....Si está desarrollando para dispositivos con jailbreak, una buena idea es usar la herramienta de línea de comandos ffmpeg desde dentro de su aplicación. es bastante fácil crear una película a partir de imágenes con un comando como:

ffmpeg -r 10 -b 1800 -i %03d.jpg test1800.mp4

Tenga en cuenta que las imágenes tienen que ser nombradas secuencialmente , y también ser colocadas en el mismo directorio. Para más información echa un vistazo a: http://electron.mit.edu / ~gsteele / ffmpeg /

Utilice AVAssetWriter para escribir imágenes como película. Ya he respondido aquí: - https://stackoverflow.com/a/19166876/1582217