Tgy31/THTinderNavigationController — pull request #10 by wiruzx (2014-12-12 23:21:05+00:00)
Title: Fix callback calls

In Swift this cause exception, because it's trying to call `length` method form `NSNull`

When you use `valueForKey:` method on `NSArray`, it returns new array: result of invoking selector "title".
But whenever viewController's title equals `nil`, there will be `NSNull` object.