Question

我为用户名创建了一个文本字段，为密码和按钮创建了另一个文本字段。现在在JSON帖子中，如果我输入了错误的详细信息，则必须为我显示错误消息。如果我输入了正确的细节，它应该转到另一个视图控制器。怎么做？

self.urlSession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

self.serviceURLReq = [[NSMutableURLRequest alloc]initWithURL:[NSURL URLWithString:@"http://dokitatesting.com/API/doctorLogin"]];


self.serviceURLReq.HTTPMethod = @"POST";

[self.serviceURLReq setValue:@"application/x-www-form-urlencoded; charset=utf-8" forHTTPHeaderField:@"Content-Type"];


NSString * dataToServer = [NSString stringWithFormat:@"UserName=%@&Password=%@",self.userNameField.text,self.passwordField.text];


NSData *postData = [dataToServer dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

NSString *postLength = [NSString stringWithFormat:@"%lu",(unsigned long)[postData length]];

[self.serviceURLReq setValue:postLength forHTTPHeaderField:@"Content-Length"];

[self.serviceURLReq setHTTPBody:postData];

if ([self.userNameField hasText] && [self.passwordField hasText]) {


    self.dataTask = [self.urlSession dataTaskWithRequest:self.serviceURLReq completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {


        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{

            //1
            AD.serverResponseDict = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

            NSLog(@"server response is %@",AD.serverResponseDict);

            dispatch_async(dispatch_get_main_queue(), ^{ // 2
                LVC = [self.storyboard instantiateViewControllerWithIdentifier:@"LoginViewController"];

                [self.navigationController pushViewController:LVC animated:YES]; // 3
            });
        });


    }];


    [self.dataTask resume];

}

这是我编写的代码，当我输入错误的详细信息时，它只是显示服务器响应的消息是（null）

Answer 1

你必须知道你何时获得这些错误，所以在登录调用中有一个完成处理程序会很好。之后，您可以通过JSON错误指定是否显示错误，或导航到另一个视图控制器。以下是在Objective-C中显示错误的方法：

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title"
                                                                         message:@"Message"
                                                                  preferredStyle:UIAlertControllerStyleAlert];
//We add buttons to the alert controller by creating UIAlertActions:
UIAlertAction *actionOk = [UIAlertAction actionWithTitle:@"Ok"
                                                   style:UIAlertActionStyleDefault
                                                 handler:nil]; //You can use a block here to handle a press on this button
[alertController addAction:actionOk];
[self presentViewController:alertController animated:YES completion:nil];

这就是你导航到另一个视图控制器的方式：

UIStoryboard* storyboard = [UIStoryboard storyboardWithName:@"storyBoardName" bundle:nil];
MemberDetailsViewController* controller = [storyboard instantiateViewControllerWithIdentifier:@"viewControllerIdentiferInStoryBoard"];

[self.navigationController pushViewController:viewControllerName animated:YES];

如何在登录详细信息无效时显示错误消息？

1 个答案: