UIActivityIndicatorView keeps animating preceding CATransition pushViewController - objective-c

Question

I'm trying stop the animation on my UIActivityIndicatorView in the same method that I push a view controller using a CATransition fade.
Instead of stopping the animation, then fading to the next view controller, the UIActivityIndicatorView contiues animating throughout the entire fade, no matter how long I set the duration.
Any ideas how I can get the spinning to stop, then push/fade in the same method?
- (void)pushView:(NSNotification *)notification {
[self.activityIndicator stopAnimating];
NextViewController* nextViewController = [[NextViewController alloc] init];
CATransition *transition = [CATransition animation];
transition.duration = 1.5f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;
[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController pushViewController:nextViewController animated:NO];
}
Edit 1
Along the same lines as David's answer, I was able to successfully stopAnimating if I used dispatch_after and delayed for a fraction of a second. Is there a better way to accomplish this?:
- (void)pushView:(NSNotification *)notification {
[self.activityIndicator stopAnimating];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.0001 * NSEC_PER_SEC), dispatch_get_main_queue(), ^(void){
NextViewController* nextViewController = [[NextViewController alloc] init];
CATransition *transition = [CATransition animation];
transition.duration = 1.5f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;
[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController pushViewController:nextViewController animated:NO];
});
}

Answer 1

I've run into something similar to this before. What you are running is called Synchronous Execution. In synchronous execution, the UI is not updated until the compiler terminates the function, a.k.a. the }. How do you get around this? Simple. Just run any methods to update the UI in an Asynchronous dispatch:
- (void)pushView:(NSNotification *)notification {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
dispatch_async(dispatch_get_main_queue(), ^(void){
[self.activityIndicator stopAnimating];
});
NextViewController* nextViewController = [[NextViewController alloc] init];
CATransition *transition = [CATransition animation];
transition.duration = 1.5f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionFade;
[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController pushViewController:nextViewController animated:NO];
});
}
Whoops! I forgot to put the other code in a plain dispatch! Try the edited code and it should work!
This way the [self.activityIndicator stopAnimating]; is run on a priority thread, while the rest of the code in the function is run in the default priority thread, effectively running the code at the same time, the way you would expect it to.
Cheers!