Question

我正在尝试为我发送到服务器的URL抓取iOS生成的参数。 iOS运行线程异步以获取参数。问题是，当我在主线程中为我的URL创建参数时，iOS async_param有时不包含在我需要的参数字典中（因为iOS尚未完成运行其线程）。

例如，如果我尝试生成包含来自两个不同线程的参数的URL请求，它应该看起来像http://myserver.com?param=my_param&async_param=my_async_param。要生成它，我使用以下代码：

-(void) sendURL{
  NSMutableDictionary *params = [NSMutableDictionary dictionary];
  //this is my param in the main thread
  [params setObject:@"my_param" forKey:@"param"];

  //get my iOS async param
  [[someIOS8Class sharedInstance] getAsyncParamWithCompletionHandler:^(NSString param)
  {
    [params setObject:param forKey:@"async_param"];
  }];

  [self sendURLWithParameters: params];
  //this is where sometimes the async param does not show up in the URL
}

如果IOSClass仅存在于iOS8上，那么处理这种情况的最佳方法是什么？

Answer 1

你应该创建一个错误/失败/无参数块然后发送网址

-(void) sendURL{
  NSMutableDictionary *params = [NSMutableDictionary dictionary];
  //this is my param in the main thread
  [params setObject:@"my_param" forKey:@"param"];

  //get my iOS async param
  [[someIOSClass sharedInstance] getAsyncParamWithCompletionHandler:^(NSString param)
  {
    // send the parameter if there's an async param
    [params setObject:param forKey:@"async_param"];
    [self sendURLWithParameters: params];
  } withFailure:^(NSError *error) {
    //Create this error if there's no async param
    [self sendURLWithParameters: params];
  }];
}

Answer 2

您可以使用信号量等待任何异步代码：

-(void)sendURL {
  NSMutableDictionary *params = [NSMutableDictionary dictionary];

  //this is my param in the main thread
  [params setObject:@"my_param" forKey:@"param"];

  //get my iOS async param
  dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
  [[someIOS8Class sharedInstance] getAsyncParamWithCompletionHandler:^(NSString param) {
    [params setObject:param forKey:@"async_param"];
    dispatch_semaphore_signal(semaphore);
 }];

 dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
 [self sendURLWithParameters: params];
 dispatch_release(semaphore);
 //this is where sometimes the async param does not show up in the URL
}

处理异步生成的参数iOS8参数的最佳方法是什么？

2 个答案: