Set contents of CALayer to animated GIF?

Question

Is it possible to set the contents of a CALayer to an animated GIF and have it display that animation? I know that I can set the contents to an image like so:

Answer 1

Well, okay, I guess this isn't that hard to do. Basically I check to see if the image is a GIF:

if ([format isEqualToString:@"gif"]){
    CAKeyframeAnimation *animation = [self createGIFAnimation:data];
    [subLayer addAnimation:animation forKey:@"contents"];
}

And as you can see, I'm calling my custom createGIFAnimation method, which looks like this:

- (CAKeyframeAnimation *)createGIFAnimation:(NSData *)data{
    NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithData:data];
    CGImageSourceRef src = CGImageSourceCreateWithData((__bridge CFDataRef)(data), nil);
    NSNumber *frameCount = [rep valueForProperty:@"NSImageFrameCount"];

    // Total loop time
    float time = 0;

    // Arrays
    NSMutableArray *framesArray = [NSMutableArray array];
    NSMutableArray *tempTimesArray = [NSMutableArray array];

    // Loop
    for (int i = 0; i < frameCount.intValue; i++){

        // Frame default duration
        float frameDuration = 0.1f;

        // Frame duration
        CFDictionaryRef cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(src,i,nil);
        NSDictionary *frameProperties = (__bridge NSDictionary*)cfFrameProperties;
        NSDictionary *gifProperties = frameProperties[(NSString*)kCGImagePropertyGIFDictionary];

        // Use kCGImagePropertyGIFUnclampedDelayTime or kCGImagePropertyGIFDelayTime
        NSNumber *delayTimeUnclampedProp = gifProperties[(NSString*)kCGImagePropertyGIFUnclampedDelayTime];
        if(delayTimeUnclampedProp) {
            frameDuration = [delayTimeUnclampedProp floatValue];
        } else {
            NSNumber *delayTimeProp = gifProperties[(NSString*)kCGImagePropertyGIFDelayTime];
            if(delayTimeProp) {
                frameDuration = [delayTimeProp floatValue];
            }
        }

        // Make sure its not too small
        if (frameDuration < 0.011f){
            frameDuration = 0.100f;
        }

        [tempTimesArray addObject:[NSNumber numberWithFloat:frameDuration]];

        // Release
        CFRelease(cfFrameProperties);

        // Add frame to array of frames
        CGImageRef frame = CGImageSourceCreateImageAtIndex(src, i, nil);
        [framesArray addObject:(__bridge id)(frame)];

        // Compile total loop time
        time = time + frameDuration;
    }

    NSMutableArray *timesArray = [NSMutableArray array];
    float base = 0;
    for (NSNumber* duration in tempTimesArray){
        //duration = [NSNumber numberWithFloat:(duration.floatValue/time) + base];
        base = base + (duration.floatValue/time);
        [timesArray addObject:[NSNumber numberWithFloat:base]];
    }

    // Create animation
    CAKeyframeAnimation* animation = [CAKeyframeAnimation animationWithKeyPath:@"contents"];

    animation.duration = time;
    animation.repeatCount = HUGE_VALF;
    animation.removedOnCompletion = NO;
    animation.fillMode = kCAFillModeForwards;
    animation.values = framesArray;
    animation.keyTimes = timesArray;
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    animation.calculationMode = kCAAnimationDiscrete;

    return animation;
}

Pretty straightforward, although I would love some tips on how to improve it.