height of leftViewController sometimes changes

I have a view with distance 16 to the top , but I find it wrong when runs on simulator



sometimes it happens , but sometimes not , that is very strange


my code

```
SlideMenuOptions.contentViewScale = 1
SlideMenuOptions.hideStatusBar = false
SlideMenuOptions.contentViewOpacity = 0.35
SlideMenuOptions.separateGestureFromScrollViewInMainViewController = true
SlideMenuOptions.lockGestureDirection = true
SlideMenuOptions.pointOfNoReturnWidth = SlideMenuOptions.leftViewWidth/2 //控制滑动多少会自动回弹或者自动弹出
switch Device.size(){
case .Screen3_5Inch,.Screen4Inch:
SlideMenuOptions.leftViewWidth = 220
case .Screen4_7Inch,.Screen5_5Inch:
SlideMenuOptions.leftViewWidth = 300
case .UnknownSize:
break
}

let main = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier(MainViewController.storyboardIdentifierNav)
let left = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier(LeftViewController.storyboardIdentifier)

let slide = SlideMenu(mainViewController: main, leftMenuViewController: left)

self.window?.rootViewController = slide
```