ios通过按钮点击异步加载图片

    imageView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight );
    [self addSubview:imageView];
    imageView.frame = self.bounds;
    [imageView setNeedsLayout];
    [self setNeedsLayout];
    [data release];
    data=nil;
}
- (UIImage*) image {
    UIImageView* iv = [[self subviews] objectAtIndex:0];
    return[iv image];
}
- (void)dealloc {
    [connection cancel];
    [connection release];
    [data release];
    [super dealloc];
}
@end

 

方法二：

复制代码
@interface UIButton (AsyncImage)
//size by point
- (void)setImageFromURL:(NSString *)urlString adjustToSize:(CGSize)size completion:(void (^)(void))completion logo:(UIImage *)logoImage; 
@end
@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();