UIKit crashes

[Hannes Käufler]

I am getting some crashreports tracing back to the theme change notification which I cannot figure out at all. maybe anyone can see whats wrong just by glancing at what I`m doing?

From the view controller where the crash is happening:

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    [NSNotificationCenter.defaultCenter addObserver:self
                                           selector:@selector(applyTheme)
                                               name:nil
                                             object:nil];
    // two more method calls ...
    [self applyTheme];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    [NSNotificationCenter.defaultCenter removeObserver:self];
}

The report in crashlytics always shows the applyTheme method to be root of the crash, with the stacktrace showing a posted notification before.

10 Foundation   -[NSNotificationCenter postNotificationName:object:userInfo:] + 72

Fatal Exception: NSInternalInconsistencyException
Tint view duration stack popped without matching push

This is the method:

- (void)applyTheme
{
    UIColor *tintColor = [RNThemeManager.sharedManager colorForKey:@"tintColor"];

    self.navigationController.navigationBar.barTintColor = tintColor;
    self.navigationController.navigationBar.tintColor = [RNThemeManager.sharedManager colorForKey:@"buttonTextColor"];
    self.view.tintColor = tintColor;
    self.someToolbar.barTintColor = tintColor;
    self.someOtherToolbar.barTintColor = tintColor;
}

The theme changing happens in a different view controller than the crash. I cannot reproduce the crash for the life of me. Am I chasing a UIKit bug? Is there something I´m doing wrong? Thanks for any help!