how to use 'presentViewController' with cover View and main page - swift

Question

A lots app, they have the cover view, like facebook, wechat...
but when I try to use presentViewController let the cover present to main page, that still in the cover vie. The following is my code:
var window: UIWindow?
var coverVC:CoverView?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
window = UIWindow(frame: UIScreen.mainScreen().bounds)
window?.backgroundColor = UIColor.lightGrayColor()
coverVC = ViewController()
coverVC?.refresh(window!.frame)
window!.makeKeyAndVisible()
return true
}
Coverview
class CoverView: UIViewController {
func refresh(frame:CGRect){
self.view.frame = frame
self.view.backgroundColor = UIColor.whiteColor()
var mainVC:mainView = mainView()
mainVC.refresh(frame)
self.dismissViewControllerAnimated(false, completion: nil)
self.presentViewController(mainVC, animated: false, completion: nil)
}
}
Main view:
class mainView: UIViewController {
func refresh(frame:CGRect){
self.view.frame = frame
self.view.backgroundColor = UIColor.blueColor()
}
}
Maybe can use other easy way to achieve the goal, that's ok.
otherwise, please don't use "UInavigationcontroller", I know that can present view, but I don't want the bar in cover view, thanks.

Answer 1

I find the correct with cover/login view, it is called SplashScreen.
And in xcode 9, you can find at [TARGETS]>[APP icons and Launch Images] (Image).(The past version, you need add "launch image" in plist file.)
Otherwise, If you doesn't want use this view, just delete "LaunchScreen".