iOS网络: NSURLConnection进行同步下载

//简单的同步请求
- (void)sendSynNetwork{
    NSLog(@"Wo are here...");
    NSString *urlString = @"http://www.baudu.com";
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0f];
    dispatch_queue_t dispatchQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(dispatchQueue, ^{
        //同步没有block

        //这样解决比较方便
        NSURLResponse *response = nil;
        NSError *error = nil;
        NSLog(@"开始同步请求");
        NSData *data = [NSURLConnection sendSynchronousRequest:urlRequest returningResponse:&response error:&error];
        if ([data length] > 0 && error == nil){
            NSLog(@"%lu bytes of data was returned.", (unsigned long)[data length]); }
        else if ([data length] == 0 && error == nil){
            NSLog(@"No data was returned.");
        }
        else if (error != nil){
            NSLog(@"Error happened = %@", error);
        }
        
    });
   NSLog(@"We are done.");
}