Question

Pressinsg the right bar button, Showed NCFSString unrecognized selector.. on restarting, I get no helpful stack trace.

 -(void)nextIntroStage{
_introStage++;
if (_introStage < _maxIntro) {
    [self showIntroPicture];
} else {
    [self finishedIntro];
}

}

 -(void)viewDidLoad {
[super viewDidLoad];
_introStage = 0;
_maxIntro = 3;

UIBarButtonItem *nextButton = [[UIBarButtonItem alloc] initWithTitle:@"Next" 
                                                               style:UIBarButtonItemStyleBordered 
                                                              target:self
                                                              action:@selector(nextIntroStage)];
self.navigationItem.rightBarButtonItem = nextButton;

Strange, switched it to leftBarButtonitem and am getting “NSURL nextIntroStage”.. but I’m not using an NSURL anywhere in my app. Some kind of memory issue, sure, but what?

Only relevant thing I can think of is in my app delegate I’m doing

    UINavigationController *nc = [[UINavigationController alloc] initWithRootViewController:viewController];
[window addSubview:nc.view];
[window makeKeyAndVisible];
[nc release];

Answer 1

The addSubview: method only retains the view you have added, not the navigation controller. By releasing that navigation controller with [nc release], you are essentially destroying that view’s navigationController.

Move the declaration for nc to your .h, initialise it as usual in your didFinishLaunchingWithOptions and release it in your dealloc.