Login Failure Still Segues to Next View Controller

问题

Though I've successfully done this before, I can't figure it out this time. I've got a basic login screen as the first VC loaded upon launch. Successful login (appropriate username/password combo from database) does appropriately allow access without any alerts. However...any incorrect combination (or no username/password at all, for that matter), results in my desired alertView, but the next VC loads anyway. What am I doing wrong? There should be no segue at all upon failure, just an alert.

LoginViewController.m

@implementation LoginViewController

- (IBAction)unwindToLoginViewController:(UIStoryboardSegue *)unwindSegue
{
}

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

        if([[self.usernameText text] isEqualToString:@""] || [[self.passwordText text] isEqualToString:@""] ) {

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

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

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

            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) 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;
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

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

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

LoginViewController.h

@interface LoginViewController : UIViewController <UITextFieldDelegate>


@property (strong, nonatomic) IBOutlet UIButton *signUpButton;
@property (strong, nonatomic) IBOutlet UIButton *forgotPasswordButton;
@property (strong, nonatomic) IBOutlet UITextField *passwordText;
@property (strong, nonatomic) IBOutlet UITextField *usernameText;

- (IBAction)loginClicked:(id)sender;
- (IBAction)backgroundTap:(id)sender;

@end

回答1:

I have found the issue. I was using the IBAction of my login button to segue between the login screen and the second VC. Because it was conditional (login success/failure), I should have CTRL clicked and dragged from the ViewController itself to the second, desired VC. Image below for example.

Fortunately, this was it. Rookie mistake on my part :/

回答2:

This line might be causing the possible issue. success = [jsonData[@"success"] integerValue]; It is updating success to a value greater than zero even in case of failure as well. By the way, you can do like this to solve it for now. Hopefully it will work

• (IBAction)loginClicked:(id)sender { NSInteger success = 0; @try {

  if([[self.usernameText text] isEqualToString:@""] || [[self.passwordText text] isEqualToString:@""] ) {
  
      [self alertStatus:@"Please enter Email and Password" :@"Sign in Failed!" :0];
  
  } else {
      NSString *post =[[NSString alloc] initWithFormat:@"username=%@&password=%@",[self.usernameText text],[self.passwordText text]];
      NSLog(@"PostData: %@",post);
  
      NSURL *url=[NSURL URLWithString:@"http://www.techinworship.com/auth.php"];
  
      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");
              [self performSegueWithIdentifier:@"login_success" sender:self];
  
          } 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]; } }

来源：https://stackoverflow.com/questions/22972483/login-failure-still-segues-to-next-view-controller