Do something when the animation of the navigation bar is complete

gistfile1.m

// in the view controller
 
UIWindow* window = [[UIApplication sharedApplication] keyWindow];
UINavigationController* navigationController = (UINavigationController *)[window rootViewController];
    
[UIView transitionWithView:self.view
                  duration:UINavigationControllerHideShowBarDuration
                   options:UIViewAnimationOptionCurveLinear
                animations:^{
    [navigationController setNavigationBarHidden:YES animated:NO];
} completion:^(BOOL finished) {
    /* do something */
}];