CIImage memory leak

Question

I'm using the below method to blur some images. Using instruments the CIImage's are leaking. I tried wrapping them in an @autoreleasepool, but no luck. Any ideas?

-(UIImage *)blurImage:(UIImage *)image withStrength:(float)strength
{
    @autoreleasepool {
        CIContext *context = [CIContext contextWithOptions:nil];
        CIImage *inputImage = [[CIImage alloc] initWithCGImage:image.CGImage];
        CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
        [filter setValue:inputImage forKey:@"inputImage"];
        [filter setValue:[NSNumber numberWithFloat:strength] forKey:@"inputRadius"];

        CIImage *result = [filter valueForKey:kCIOutputImageKey];
        float scale =  [[UIScreen mainScreen] scale];
        CIImage *cropped=[result imageByCroppingToRect:CGRectMake(0, 0, image.size.width*scale, image.size.height*scale)];
        CGRect extent = [cropped extent];
        CGImageRef cgImage = [context createCGImage:cropped fromRect:extent];
        UIImage *returnImage = [UIImage imageWithCGImage:cgImage].copy;

        CGImageRelease(cgImage);

        return returnImage;
    }

}

Answer 1

did you try to put CIImages to nil ?

-(UIImage *)blurImage:(UIImage *)image withStrength:(float)strength
{      
       //your code
       CGImageRelease(cgImage);

       cropped=nil;
       result = nil;
       inputImage = nil;
       context = nil;

       return returnImage;
     }
 }

Answer 2

I see the same leak you're seeing when profiling the code. Try this instead which seems to avoid the leak and give you the same results:

- (UIImage*)blurImage:(UIImage*)image withStrength:(float)strength
{
    @autoreleasepool {
        CIImage* inputImage = [[CIImage alloc] initWithCGImage:image.CGImage];
        CIFilter* filter = [CIFilter filterWithName:@"CIGaussianBlur"];
        [filter setValue:inputImage forKey:@"inputImage"];
        [filter setValue:[NSNumber numberWithFloat:strength] forKey:@"inputRadius"];

        CIImage* result = [filter valueForKey:kCIOutputImageKey];
        float scale = [[UIScreen mainScreen] scale];
        CIImage* cropped = [result imageByCroppingToRect:CGRectMake(0, 0, image.size.width * scale, image.size.height * scale)];

        return [[UIImage alloc] initWithCIImage:cropped];
    }
}