IOS How to create movie from images

/* Create movie from images */
+ (void) createMovieFromImages:(NSString*) folderName file:(NSString *) fileName withSize:(CGSize)imageSize imageArray:(NSMutableArray*) imageArray {
    int duration =  60.0; // Movie duration
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectoryPath = [paths objectAtIndex:0];
    NSString *myFilePath;
    if([folderName length] == 0) {
        myFilePath = [documentsDirectoryPath stringByAppendingPathComponent:fileName];
    } else {
        myFilePath = [[[[documentsDirectoryPath stringByAppendingString:@"/"] stringByAppendingString:folderName]
                       stringByAppendingString:@"/"] stringByAppendingString:fileName];
    }
   
     NSError *error = nil;
   
    /*prepare to write the movie*/
    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:myFilePath] fileType:AVFileTypeQuickTimeMovie error:&error];
    /* AVFileTypeQuickTimeMovie ,AVFileTypeMPEG4 */
   
    NSParameterAssert(videoWriter);
   
    NSDictionary *videoSettings =
    [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecH264,AVVideoCodecKey,[NSNumber numberWithInt:imageSize.width],AVVideoWidthKey,
     [NSNumber numberWithInt:imageSize.height],AVVideoHeightKey, nil];
   
    AVAssetWriterInput* writerInput =
    [[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
                                        outputSettings:videoSettings] retain];
   
    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                     assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:nil];
   
    NSParameterAssert(writerInput);
    NSParameterAssert([videoWriter canAddInput:writerInput]);
    [videoWriter addInput:writerInput];
   
    //start writing
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];
   
    CVPixelBufferRef buffer = NULL;
    /*buffer = [self pixelBufferFromCGImage:[[imageArray objectAtIndex:0] CGImage] andSize:CGSizeMake(imageSize.width,imageSize.height)];
    CVPixelBufferPoolCreatePixelBuffer(NULL,adaptor.pixelBufferPool,&buffer);
    [adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];*/
   
    //loop through image array
    int y = [imageArray count];
    int x = 0;
    int framePerSecond = 0;
    if(duration <= y) {
        float temp = (float)y/(float)duration;
        framePerSecond = lroundf(temp);
    } else {
        framePerSecond = duration/y;
    }
   
    NSLog(@"framePerSecond:%d total image:%d duration:%d",framePerSecond, y, duration);
    while(x < y)  {
        if(writerInput.readyForMoreMediaData == YES){
            if(duration > y) {
                for (int i = 1; i <= duration; i++) {
                    CMTime frameTime = CMTimeMake(1,1);
                    CMTime lastTime = CMTimeMake(i,1);
                    CMTime presentTime = CMTimeAdd(lastTime,frameTime);
                    UIImage *image = [Global getImageFromAlbum:folderName file:[imageArray objectAtIndex:x]];
                    buffer = [self pixelBufferFromCGImage:image.CGImage andSize:CGSizeMake(imageSize.width,imageSize.height)];
                   
                    [adaptor appendPixelBuffer:buffer
                          withPresentationTime:presentTime];
                    CVBufferRelease(buffer);
                    if(i%framePerSecond == 0) {
                        x = x + 1;
                        if(x >= y) break;                       
                    }
                }
            } else {
                CMTime frameTime = CMTimeMake(1,framePerSecond);
                CMTime lastTime = CMTimeMake(x,framePerSecond);
                CMTime presentTime = CMTimeAdd(lastTime,frameTime);
                UIImage *image = [Global getImageFromAlbum:folderName file:[imageArray objectAtIndex:x]];
                buffer = [self pixelBufferFromCGImage:image.CGImage andSize:CGSizeMake(imageSize.width,imageSize.height)];
               
                [adaptor appendPixelBuffer:buffer
                      withPresentationTime:presentTime];
                CVBufferRelease(buffer);
                x = x + 1;
            }
        }
    }
   
    //finish writing
    [writerInput markAsFinished];
    [videoWriter finishWriting];
   
    //clean up
    CVPixelBufferPoolRelease(adaptor.pixelBufferPool);
    [videoWriter release];
    [writerInput release];
    [imageArray removeAllObjects];
}