NSURLConnection 不响应Delegate方法

//设置请求超时时间为30s
NSMutableURLRequest *requestLoad = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://box.zhangmen.baidu.com/bdlrc/93/9351.lrc"] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:30.0];

self.connection = [[NSURLConnection alloc] initWithRequest:requestLoad delegate:self];
//开启一个runloop，使它始终处于运行状态

UIApplication *app = [UIApplication sharedApplication];
app.networkActivityIndicatorVisible = YES;
finished = NO;
while (!finished)
{
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}