Is it possible to check whether an identifier exists in a storyboard before instantiating the object?

Question

In my code I have this line, but I was wondering if there is way to check whether @\"SomeController\" exists before I use it with the \"instantiateViewControllerWit

Answer 1

You can use valueForKey: on UIStoryboards. UIStoryboards have a key called "identifierToNibNameMap", its value is an NSDictionary with the UIViewControllers in that storyboard. This inner NSDictionary uses the viewcontroller's names as keys so you can actually check if a viewcontroller exists in a storyboard with the following code:

if ([[storyboard valueForKey:@"identifierToNibNameMap"] objectForKey:myViewControllerName]) {
    // the view controller exists, instantiate it here
    UIViewController* myViewController = [storyboard instantiateViewControllerWithIdentifier:myViewControllerName];
} else {
    //the view controller doesn't exist, do fallback here
}

Note: Apple has been known to reject apps that query the underlying properties of cocoa classes using valueForKey:. These underlying properties could change at any time in the future, breaking app functionality without warning. There is no deprecation process for these things.