Objective -C How to create a video from an NSMutableArray?

Question

I have an NSMutableArray of images I need to create a video and save as .mp4 format I tried a code found in many places to produce a video from images. But it does not work. It creates a blank file

-(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size duration:(int)duration
{
    NSError *error = nil;

    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];

    //Start a session:
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];

    CVPixelBufferRef buffer = NULL;

    //convert uiimage to CGImage.

    for (int i = 0; i < [array count]; i++) {  //NSMutableArray
        buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
        NSLog(@"%@",[[array objectAtIndex:i] CGImage]);
    }
    [adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];

    //Write samples:


    //Finish the session:
    [writerInput markAsFinished];
}

-(CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES],   kCVPixelBufferCGImageCompatibilityKey,
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
                             nil];
    CVPixelBufferRef pxbuffer = NULL;

    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, self.view.frame.size.width,
                                          self.view.frame.size.height, kCVPixelFormatType_32ARGB, (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, self.view.frame.size.width,
                                                 self.view.frame.size.height, 8, 4*self.view.frame.size.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;
}

What is wrong?

Can anyone help me to find a solution please?

Is there any other way that I can create video from images?

Answer 1

Use [videowriter finishWriting]; after [writerInput markAsFinished];

in writeImageAsMovie method.

In ios7 its deprecated ,so use

[videoWriter finishWritingWithCompletionHandler:^(){
    NSLog (@"finished writing");
}];

this is very important for the video creation.Thus solved the issue.

Thanks to all for the help.