调用网络服务时显示警报

发布于 2024-10-21 03:21:11 字数 641 浏览 7 评论 0原文

我有以下代码。

UIActivityIndicator *activity = [[UIActivityIndicator alloc] initWithActivityIndicatorStyle:
                                                    UIActivityIndicatorStyleWhite];


UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Processing" delegate:self otherButtonTitles:nil];
   [alert addSubview:activity];    
   [activity startAnimating];    
   [alert show];

WebServiceController *web = [[WebServiceController alloc]init];

NSDictionary *dict = [web getDetails];

问题是警报没有显示。 WebServiceController 是一个 XML 解析器，它从指定的 URL 获取详细信息并返回它们。应在调用服务时显示警报，因为获取详细信息需要时间。但它仅在服务呼叫结束后才显示警报。这是为什么？

原文

i have the following code.

UIActivityIndicator *activity = [[UIActivityIndicator alloc] initWithActivityIndicatorStyle:
                                                    UIActivityIndicatorStyleWhite];


UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Processing" delegate:self otherButtonTitles:nil];
   [alert addSubview:activity];    
   [activity startAnimating];    
   [alert show];

WebServiceController *web = [[WebServiceController alloc]init];

NSDictionary *dict = [web getDetails];

The problem is that the alert is not getting displayed. The WebServiceController is an XML parser which gets details from a specified URL and returns them. The alert should be shown while the service is called as it takes time to get the details. But it displays the alert only after the service call is over. Why is that?

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薄荷→糖丶微凉 2024-10-28 03:21:11

因为[alert show]需要动画，由于服务控制器调用发生在主线程上，主线程正忙于执行服务调用，阻塞了alert view动画的执行。

您需要在后端线程上执行ServiceCall，请参阅NSOperation或PerformSelectorOnBackgroundThread，确保将具有AlertView的ViewController的委托传递给后端线程，服务调用完成后立即回调该委托。确保使用performSelectorOnMainThread 在主线程上执行回调调用。所有与 UI 相关的调用都应在主线程上执行。

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心在旅行 2024-10-28 03:21:11

添加到上面的帖子中，您必须像这样编写警报：

UIActivityIndicator *activity = [[UIActivityIndicator alloc] initWithActivityIndicatorStyle:
                                                    UIActivityIndicatorStyleWhite];


UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Processing" delegate:self otherButtonTitles:nil];
   [alert addSubview:activity];    
   [activity startAnimating];    
   [alert show];

[self performSelectorInBackground:@selector(doTheWork) object:nil];

您需要声明一个函数 (doTheWork)，它将处理 Web 服务调用，如下所示：

-(void)doTheWork {

WebServiceController *web = [[WebServiceController alloc]init];

NSDictionary *dict = [web getDetails];

[alert dismissWithClickedButtonIndex:0 animated:YES]; //dismissing the alert

}

Adding to the above post, you have to write the alert like this:

UIActivityIndicator *activity = [[UIActivityIndicator alloc] initWithActivityIndicatorStyle:
                                                    UIActivityIndicatorStyleWhite];


UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Processing" delegate:self otherButtonTitles:nil];
   [alert addSubview:activity];    
   [activity startAnimating];    
   [alert show];

[self performSelectorInBackground:@selector(doTheWork) object:nil];

You need to declare a function (doTheWork) which will take care of the web service call as follows:

-(void)doTheWork {

WebServiceController *web = [[WebServiceController alloc]init];

NSDictionary *dict = [web getDetails];

[alert dismissWithClickedButtonIndex:0 animated:YES]; //dismissing the alert

}

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