Open Library > Container View. If you use that, it creates that View Controller. In any case, I tried both ways with the same result.

Here is an example with macOS:

When you say "5. you can keep the content layout and frame layout ON", what do you mean?

I have opened a new thread. I have been searching and trying things but still, I do not understand your sketch solution. Are you sure this is macOS and storyboards? It looks very new to me and I do not know how to learn.

These are some of the things I tried: var controller: NSWindowController? @IBAction func loadSecondFromMenu(_ sender: NSButton) { let storyboard: NSStoryboard = NSStoryboard(name: "Main", bundle: nil) let myViewController = storyboard.instantiateController(withIdentifier: "SecondView") as? SecondViewController //self.view.window?.contentViewController = myViewController //error: Value of type 'AppDelegate' has no member 'view'         //controller?.contentViewController = myViewController //no error, and it does not open any window }

I have a window controller and two views. With my code, I open view1. I try to open view2 with code. I do not understand your code. It gives me error.

That is just fantastic! I have been hours searching and trying things and you solved in a minute!. Thank you!

I want to animate (using any method) the change of the label's text in a macOS app. With the code I provide, the change occurs when I click the button. I see no animation and no delay. import Cocoa class ViewController: NSViewController {     @IBOutlet weak var label1: NSTextField!     override func viewDidLoad() {         super.viewDidLoad()     }     @IBAction func button2(_ sender: NSButton) {         NSAnimationContext.runAnimationGroup({ (context) in             context.duration = 4.0             label1.stringValue = "long, long text"             label1.animator().sizeToFit()         })     } }