Question

所以我一直在尝试为网站创建一个应用程序，并且我已经获得了＃34;登录＆＃34;页面工作，除非它不能转换到下一个视图。

这是我认为导致问题的代码：

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
 {
     NSString *str=[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
     //NSLog(@"%@", str);
     if ([str rangeOfString:@"The username or password you provided is invalid. Please try again."].location == NSNotFound) {
         loginPageStatusLabel.text = @"Correct";
         NSLog(@"Correct Login");

         [self performSegueWithIdentifier:@"toHome" sender:self];


     } else {
         loginPageStatusLabel.text = @"Incorrect";
         NSLog(@"Login Failed");
     }

 }];

*断言失败 - [UIKeyboardTaskQueue waitUntilAllTasksAreFinished]，/ SourceCache / UIKit_Sim / UIKit-2935.137 / Keyboard / UIKeyboardTaskQueue.m：368 2014-05-11 00：06：51.426 LoginTests [3381：3e03] * 由于未捕获的异常终止应用程序＆＃39; NSInternalInconsistencyException＆＃39;，原因：＆＃39; - [UIKeyboardTaskQueue waitUntilAllTasksAreFinished]＆＃39 ;可能只能从主线程调用。＆＃39; waitUntilAllTasksAreFinished]＆＃39;可能只能从主线程调用。

每当我尝试＆＃34;登录＆＃34;时，就会抛出错误。如果我独自运行，那么Segue就会工作，所以我假设问题是应用程序试图在它准备就绪之前进入下一个View并导致错误。

我是Obj-C的新手，所以如果我没有张贴足够的信息或者没有用正确的名字打电话，请通知我。

谢谢！

Answer 1

我不知道您为queue参数提供了什么值，但鉴于您的完成块正在执行必须在主线程上进行的UI更新，您可以使用[NSOperationQueue mainQueue]（或手动将此代码分派到主队列）。此queue参数指定应将完成块添加到哪个队列，并且因为您在完成块中执行与UI相关的操作，所以必须在主线程上完成此操作。

更正后，如果您仍然有断言错误，可以添加exception breakpoint，这将有助于确切地确认发生此断言错误的位置。或者查看堆栈跟踪。

除了使用[NSOperationQueue mainQueue]之外，我还建议做一些更强大的错误处理：

[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
 {
     if (!data) {
         // for example, no internet connection or your web server is down

         NSLog(@"request failed: %@", error);
         return;
     }

     if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
         int statusCode = [(NSHTTPURLResponse *)response statusCode];

         if (statusCode != 200) {
             // for example, 404 would mean that your web site said it couldn't find the URL
             // anything besides 200 means that there was some fundamental web server error

             NSLog(@"request resulted in statusCode of %d", statusCode);
             return;
         }
     }

     // if we got here, we know the request was sent and processed by the web server, so now
     // let's see if the login was successful.

     NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

     // I'm looking for "Welcome" ... I doubt that's right (but I don't have access to 
     // your web server, so I'm guessing). But the idea is that you have to find whatever
     // appears after successful login that is not in the response if login failed

     if ([responseString rangeOfString:@"Welcome"].location != NSNotFound) {
         loginPageStatusLabel.text = @"Correct";
         NSLog(@"Correct Login");

         [self performSegueWithIdentifier:@"toHome" sender:self];
     } else {
         loginPageStatusLabel.text = @"Incorrect";
         NSLog(@"Login Failed");
     }
 }];

Segue抛出NSInternalInconsistencyException，使用NSURLConnection sendAsynchronousRequest

1 个答案: