Unbalanced calls to begin/end appearance transitions

Hi, maybe I do something wrong, but when I add LoginController and check if I logged or not logged in then I see
2016-03-09 03:59:50.400 SlideMenuControllerSwift[2738:84867] Unbalanced calls to begin/end appearance transitions for .

My MainViewController

override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
let prefs:NSUserDefaults = NSUserDefaults.standardUserDefaults()
let isLoggedIn:Int = prefs.integerForKey("ISLOGGEDIN") as Int
if (isLoggedIn != 1) {
delegate?.changeViewController(LeftMenu.Login)
} else {
print("Logged in");
}
}

My LeftViewController

func changeViewController(menu: LeftMenu) {
switch menu {
case .Main:
self.slideMenuController()?.changeMainViewController(self.mainViewController, close: true)
case .Logout:
logout()
case .Login:
self.slideMenuController()?.changeMainViewController(self.loginController, close: true)
}
}

```
func logout(){
let appDomain = NSBundle.mainBundle().bundleIdentifier
NSUserDefaults.standardUserDefaults().removePersistentDomainForName(appDomain!)

changeViewController(LeftMenu.Main)
}
```

Reproduce the warning using MainViewController.viewDidAppear and the LeftViewController.changeViewController path, focusing on the .Login case and changeMainViewController call. Trace the login transition and its surrounding appearance callbacks; done means switching between Main, Login, and Logout no longer emits an unbalanced appearance-transition warning.

Written by the indexing model from the issue text.