add UIViewController in subview

Question

I don\'t know if this is the right key to search \"add UIViewController in subview\". As what you can see in my image ,there are two ViewController, the main and the second

Answer 1

let controller:SecondViewController = self.storyboard!.instantiateViewController(withIdentifier: "secondViewController") as! SecondViewController

controller.view.frame = self.view.bounds

controller.willMove(toParent: self)

self.view.addSubview(controller.view)

self.addChild(controller)

controller.didMove(toParent: self)