代码不断传递数据崩溃

Question

我正在用登录系统构建我的第一个iOS应用程序。我之前已经构建了一些简单的东西，但这已经处于一个全新的水平。目前我可以登录并从服务器获取一些数据。然后该应用程序执行model segue至MainView并附加MainController。

当我登录时，应用程序从服务器获取token和success。该令牌对于服务器的进一步请求是必需的。但是，我似乎无法弄清楚如何将令牌传递给MainController。无论我尝试什么，应用程序崩溃都会发生未知错误。

现在 - 与下面的代码 - 它抛出：

2014-10-11 14:30:14.077 LoginScreen[29076:4688502] -[UINavigationController setXAuthToken:]: unrecognized selector sent to instance 0x7bfd1140 2014-10-11 14:30:14.104 LoginScreen[29076:4688502] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UINavigationController setXAuthToken:]: unrecognized selector sent to instance 0x7bfd1140'

ViewController.h

#import <UIKit/UIKit.h> 
#import "MainController.h" 

@interface ViewController : UIViewController <UITextFieldDelegate> 
@property (weak, nonatomic) IBOutlet UITextField *txtUsername; 
@property (weak, nonatomic) IBOutlet UITextField *txtPassword; 

- (IBAction)sigininClicked:(id)sender; 

- (IBAction)backgroundTap:(id)sender; 
@end 

ViewController.m

#import "ViewController.h" 

@interface ViewController() 

@end 

@implementation ViewController 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 
} 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

- (IBAction)sigininClicked:(id)sender { 
    NSInteger success = 0; 
    @try { 

     if([[self.txtUsername text] isEqualToString:@""] || [[self.txtPassword text] isEqualToString:@""]) { 

      [self alertStatus:@"Please enter Email and Password" :@"Sign in Failed!" :0]; 

     } else { 
      NSString *post =[[NSString alloc] initWithFormat:@"username=%@&password=%@",[self.txtUsername text],[self.txtPassword text]]; 
      NSLog(@"PostData: %@",post); 

      NSURL *url=[NSURL URLWithString:@"http://www.mywebsite.com/auth"]; 

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

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

      NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init]; 
      [request setURL:url]; 
      [request setHTTPMethod:@"POST"]; 
      [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; 
      [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; 
      [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"]; 
      [request setHTTPBody:postData]; 

      //[NSURLRequest setAllowsAnyHTTPSCertificate:YES forHost:[url host]]; 

      NSError *error = [[NSError alloc] init]; 
      NSHTTPURLResponse *response = nil; 
      NSData *urlData=[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; 

      NSLog(@"Response code: %ld", (long)[response statusCode]); 

      if ([response statusCode] >= 200 && [response statusCode] < 300) 
      { 
       NSString *responseData = [[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding]; 
       NSLog(@"Response ==> %@", responseData); 

       NSError *error = nil; 
       NSDictionary *jsonData = [NSJSONSerialization 
              JSONObjectWithData:urlData 
              options:NSJSONReadingMutableContainers 
              error:&error]; 

       success = [jsonData[@"success"] integerValue]; 
       NSLog(@"Success: %ld",(long)success); 

       if(success == 1) 
       { 
        NSLog(@"Login SUCCESS"); 
       } else { 

        NSString *error_msg = (NSString *) jsonData[@"error_message"]; 
        [self alertStatus:error_msg :@"Sign in Failed!" :0]; 
       } 

      } else { 
       //if (error) NSLog(@"Error: %@", error); 
       [self alertStatus:@"Connection Failed" :@"Sign in Failed!" :0]; 
      } 
     } 
    } 
    @catch (NSException * e) { 
     NSLog(@"Exception: %@", e); 
     [self alertStatus:@"Sign in Failed." :@"Error!" :0]; 
    } 
    if (success) { 

     [self performSegueWithIdentifier:@"login_success" sender:self]; 
    } 
} 

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 
{ 
    if ([segue.identifier isEqualToString:@"login_success"]) { 
     MainController *controller = (MainController *)segue.destinationViewController; 
     controller.xAuthToken = @"test string"; 
    } 
} 

- (void) alertStatus:(NSString *)msg :(NSString *)title :(int) tag 
{ 
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title 
                 message:msg 
                 delegate:self 
               cancelButtonTitle:@"Ok" 
               otherButtonTitles:nil, nil]; 
    alertView.tag = tag; 
    [alertView show]; 
} 

- (IBAction)backgroundTap:(id)sender { 
    [self.view endEditing:YES]; 
} 

-(BOOL) textFieldShouldReturn:(UITextField *)textField { 
    [textField resignFirstResponder]; 
    return YES; 
} 

@end 

MainController.h

#import <Foundation/Foundation.h> 

@interface MainController : UIViewController 

@property (nonatomic,strong) NSString *xAuthToken; 

@end 

MainController.m

#import "MainController.h" 

@interface MainController() 

@end 

@implementation MainController 

- (void)viewDidLoad 
{ 
    NSLog(@"%@",_xAuthToken); 
} 

@end 

Answer 1

堆栈跟踪告诉你问题是什么 - 你想设置一个UINavigationController的XAuthToken财产 - 但一个UINavigationController没有这个属性。

您的MainController实例嵌入在UINavigationController中，所以这就是您从destinationViewController中获得的prepareForSegue。

你需要访问视图控制器堆栈 -

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 
{ 
    if ([segue.identifier isEqualToString:@"login_success"]) { 
     UINavigationController *navController = (UINavigationController *)segue.destinationViewController; 
     MainController *controller = (MainController *)navController.topViewController 
     controller.xAuthToken = @"test string"; 
    } 
}