Question

I am using xcode 4.2 and ARC. Below is the code I am using. When I click on any button my application crashes and it highlights this code in main.m

Sometimes I get this error

-[__NSCFTimer parentLogin:]: unrecognized selector sent to instance

and sometimes application crashes without any error.

return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));

My code is:

In my ViewController.m I am using this code to get to the ChooseLogin view controller.

- (IBAction)action:(id)sender {


    ChooseLogin *loginScreen = [[ChooseLogin alloc] initWithNibName:@"ChooseLogin" bundle:nil];
    [UIView beginAnimations:@"flipview" context:nil];
    [UIView setAnimationDuration:2];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:NO];
    [self.view addSubview:loginScreen.view];
    [UIView commitAnimations];
}

Then in ChooseLogin.m:

@implementation ChooseLogin


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


- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (IBAction)parentLogin:(id)sender {

    NSLog(@":::::::");

    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

    NSString *passwd = [prefs stringForKey:@"password"];

    NSLog(@"data saved");

    if (passwd == nil) {


    CreatePassword *cPassword = [[CreatePassword alloc] initWithNibName:@"CreatePassword" bundle:nil ];
        [UIView beginAnimations:@"flipview" context:nil];
        [UIView setAnimationDuration:1];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:NO];
        [self.view addSubview:cPassword.view];
        [UIView commitAnimations];

    }else {

        UserPassword *uPasswd = [[UserPassword alloc] initWithNibName:@"UserPassword" bundle:nil];
        [UIView beginAnimations:@"flipview" context:nil];
        [UIView setAnimationDuration:1];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:NO];
        [self.view addSubview:uPasswd.view];
        [UIView commitAnimations];

    }
}

- (IBAction)childLogin:(id)sender {

    ChildLogin *loginScreen = [[ChildLogin alloc] initWithNibName:@"ChildLogin" bundle:nil];
    [UIView beginAnimations:@"flipview" context:nil];
   // [UIView setAnimationDuration:1];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:NO];
    [self.view addSubview:loginScreen.view];
    [UIView commitAnimations];
}

@end

Answer 1

-[__NSCFTimer parentLogin:]: unrecognized selector sent to instance

This means that a message is being sent to a class that the class doesn’t recognize — you either haven’t written this custom selector (function), or somehow a function is being sent to the wrong class and therefore isn’t recognized. XCode is usually pretty good about catching these when trying to write code, but it doesn’t seem to check for them in XIB files.

The most frequent cause of this type of issue, in my experience, is when you delete or rename a function, and forget to update the XIB file associated with that class — or you do update it, and it adds the new version of the function, without forgetting the old one.