//根据图片的链接获取图片的宽高- (CGSize)downloadImageSizeWithURL:(id)imageURL{    NSURL *URL = nil;    if([imageURL isKindOfClass:[NSURL class]]){        URL = imageURL;    }    if([imageURL isKindOfClass:[NSString class]]){        URL = [NSURL URLWithString:imageURL];    }    if(URL == nil)        return CGSizeZero; #ifdef dispatch_main_sync_safe    if([[SDImageCache sharedImageCache] diskImageExistsWithKey:absoluteString]){        UIImage* image = [[SDImageCache sharedImageCache] imageFromMemoryCacheForKey:absoluteString];        if(!image){            NSData* data =http://www.mamicode.com/ [[SDImageCache sharedImageCache] performSelector:@selector(diskImageDataBySearchingAllPathsForKey:) withObject:URL.absoluteString];            image = [UIImage imageWithData:data];        }        if(image){            return image.size;        }    }#endif        CGSize size = CGSizeZero;    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:URL];    NSString *pathExtendsion = [URL.pathExtension lowercaseString];        if([pathExtendsion isEqualToString:@"png"]){        size = [self downloadPNGImageSizeWithRequest:request];    }else if([pathExtendsion isEqual:@"gif"]){        size = [self downloadGIFImageSizeWithRequest:request];    }else{        size = [self downloadJPGImageSizeWithRequest:request];    }        if(CGSizeEqualToSize(CGSizeZero, size)){        NSData* data =http://www.mamicode.com/ [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:URL] returningResponse:nil error:nil];        UIImage* image = [UIImage imageWithData:data];        if(image){#ifdef dispatch_main_sync_safe            [[SDImageCache sharedImageCache] storeImage:image recalculateFromImage:YES imageData:data forKey:URL.absoluteString toDisk:YES];#endif            size = image.size;        }    }    return size;}

原帖地址：http://blog.csdn.net/li6185377/article/details/26225799