autorelease my code

// controller.m   调用下载接口.类方法
[YJDownloadManager goTodownload];

// YJDownloadManager.m
+ (void)goTodownload
{
// code .....

    [[TCBlobDownloadManager sharedInstance] setMaxConcurrentDownloads:1];
    for (NSString *urlKey in urlDic.allKeys) {
        
        // 下载该url，下载到Documents/offlineMedia/[courseId]
        // TODO: 使用第三方库做队列code
        NSURL *url = [NSURL URLWithString:urlKey];
        NSString *path = [NSFileManager directoryPath:[NSString stringWithFormat:@"offlineMedia/%@", courseId]];
        [[TCBlobDownloadManager sharedInstance] startDownloadWithURL:url customPath:path firstResponse:^(NSURLResponse *response) {
            NSURL *requestUrl = [response URL ];
            NSLog(@"%@", requestUrl.lastPathComponent);
        } progress:^(float receivedLength, float totalLength, NSInteger remainingTime) {
            NSLog(@"receivedLength %f, totalLength %f", receivedLength, totalLength);
        } error:^(NSError *error) {
            NSLog(@"下载出错:%@", [error localizedDescription]);
        } complete:^(BOOL downloadFinished, NSString *pathToFile) {
            if (downloadFinished) {
                NSLog(@"%@下载完成", pathToFile);
            }else{
                [[NSFileManager defaultManager] removeItemAtPath:pathToFile error:nil];
            }
            
        }];
        
    }
}