@interface UIButton (AsyncImage)

 

- (void)setImageFromURL:(NSString *)urlString adjustToSize:(CGSize)size completion:(void (^)(void))completion logo:(UIImage *)logoImage;

 

 

 

@implementation UIButton (AsyncImage)

 

- (void)setImageFromURL:(NSString *)urlString adjustToSize:(CGSize)size completion:(void (^)(void))completion logo:(UIImage *)logoImage

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        UIImage *image = nil;

        NSURL *url = [NSURL URLWithString:urlString];

        NSData *data = [NSData dataWithContentsOfURL:url];

        image = [UIImage imageWithData:data];

         

        if (image) {

            if (!CGSizeEqualToSize(size, CGSizeZero)) {

                image = [UIImage imageWithCGImage:image.CGImage scale:[self scaleImage:image adjustToSize:size] orientation:image.imageOrientation];

            }

            if (logoImage) {

                image = [self addLogoImage:logoImage toImage:image];

            }

             

            dispatch_async(dispatch_get_main_queue(), ^{

                [self setImage:image forState:UIControlStateNormal];

                completion();

            });

        }

        else {

            NSLog(@"async load error.");

        }

    });

 

- (CGFloat)scaleImage:(UIImage *)image adjustToSize:(CGSize)size

    CGFloat xScale = size.width / image.size.width;

    CGFloat yScale = size.height / image.size.height;

     

    return 1.0 / MIN(xScale, yScale);

 

- (UIImage *)addLogoImage:(UIImage *)logo toImage:(UIImage *)img

    //get image width and height

    CGFloat scale = [UIScreen mainScreen].scale;

    int w = scale * img.size.width;

    int h = scale * img.size.height;

    int logoWidth = logo.scale * logo.size.width;

    int logoHeight = logo.scale * logo.size.height;

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

     

    //create a graphic context with CGBitmapContextCreate

    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);

    CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);

    CGContextDrawImage(context, CGRectMake(w - logoWidth, 0, logoWidth, logoHeight), [logo CGImage]);

    CGImageRef imageMasked = CGBitmapContextCreateImage(context);

    CGContextRelease(context);

    CGColorSpaceRelease(colorSpace);

     

    return [UIImage imageWithCGImage:imageMasked scale:scale orientation:img.imageOrientation];