Load NIB from variable-Collection of common programming errors
You cannot instantiate “UIViewController” with arbitrary NIBs, you have to instantiate “[whatever your custom view controller class is]” with the NIB for that class.
It’s crashing because it’s trying to access properties that don’t exist in UIViewController.
If you want to do this kind of dynamic view-controller loading, you need to do a bit more work, and use the special Class class method that lets you instantiate an object using a string for the class name, instead of hard-coded.
Sometehing like:
Class viewControllerClass = NSClassFromString( nibVar );
UIViewController* aController = (UIViewController*) [[viewControllerClass alloc] initWithNibName:nibVar bundle:nil];