Open Radar

 
Summary:
UIViewController's separateSecondaryViewControllerForSplitViewController(_:)

should return type UIViewController?, but it instead returns type UIViewController.

This is important for 2 reasons:
1. By default, all VCs besides UINavigationController simply return nil.
2. It's impossible to override UINavigationController's method to return nil in a subclass.

Steps to Reproduce:
1. Create a UISplitViewController project.
2. Create a custom UIViewController subclass named ShowProblemViewController (see below).
3. Designate the split VC's primary VC to be of kind ShowProblemViewController (this can be done in Storyboard).
4. Run

class ShowProblemViewController: UIViewController{
    
    override func separateSecondaryViewControllerForSplitViewController(splitViewController: UISplitViewController) -> UIViewController {
        
        let returned: UIViewController? = super.separateSecondaryViewControllerForSplitViewController(splitViewController)
        
        if let nonNil = returned{
            println("not nil")
        }
        else{
            println("nil...")
        }
        
        return returned!
    }
}

Expected Results:
Should print "not nil".

Actual Results:
Prints "nil".

Version:
Version 6.3.2 (6D2105)