iOS ASIHttpRequest 和 AFNetWorking 实时监测下载进度

@property (nonatomic, retain) AFHTTPRequestOperation *operation;

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://dlsw.baidu.com/sw-search-sp/soft/2a/25677/QQ_V4.0.2.1427684136.dmg"]];

    //下载附件

self.operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

_operation.outputStream  = [NSOutputStream outputStreamToFileAtPath:path append:NO];

    [_operation start];

    //下载进度控制

    __block TestWifiSpeedVC *weakSelf = self;

     [_operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {

}