MKNetworkKit下载图片并显示在UIImageView上

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- (IBAction)onClick:(id)sender {
    NSMutableDictionary *imageDic = [[NSMutableDictionary alloc] init];
    //获取本地沙箱的缓存路径
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *cachesDirectory = paths[0];
    NSString *downloadPath = [cachesDirectory stringByAppendingPathComponent:@"test1.jpg"];
    
    //先从本地获取缓存图片
    UIImage *image = [UIImage imageWithContentsOfFile:downloadPath];
    
    //如果从本地缓存中获取为空，那么再从应用资源中获取一次
    if (image == nil) {
        image = [UIImage imageNamed:@"test1.jpg"];
    }
    
    if (nil != image) {
        [imageDic setObject:image forKey:@"image"];
        NSLog(@"缓存有图片！");
        _imageView1.image = image;
    }
    
    //如果本地缓存图片为空，则远程请求，并缓存到本地
    if(image == nil) {
        
        NSString *path = [[NSString alloc] initWithFormat:@"/service/download.php?email=%@&FileName=test1.jpg",@"gs.654586026@qq.com"];
        path = [path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    
        MKNetworkEngine *engine = [[MKNetworkEngine alloc] initWithHostName:@"51work6.com" customHeaderFields:nil];
    
        MKNetworkOperation *downloadOperation = [engine operationWithPath:path params:nil httpMethod:@"POST"];
        [downloadOperation addDownloadStream:[NSOutputStream outputStreamToFileAtPath:downloadPath append:TRUE]];
    
        [downloadOperation onDownloadProgressChanged:^(double progress) {
        NSLog(@"download progress: %.2f%%", progress*100.0);
        _progressView.progress = progress;
        }];
    
        [downloadOperation addCompletionHandler:^(MKNetworkOperation *operation) {
        
        NSLog(@"download file finished!");
        UIImage *image = [UIImage imageWithContentsOfFile:downloadPath];
        _imageView1.image = image;
            
        } errorHandler:^(MKNetworkOperation *errorOp, NSError* err) {
            NSLog(@"MKNetwork请求错误 : %@", [err localizedDescription]);
        }];
    [engine enqueueOperation:downloadOperation];
    }
}