At what stage of the ViewController lifecycle should its main view be replaced?

The main view (view) in UIViewController should be replaced in the loadView() method. This method is called by the system when the controller loads its view. If you want to create and assign a custom view instead of the default one, you need to override loadView() and assign your UIView to the view property.

Example:

override func loadView() {
    let customView = UIView()
    customView.backgroundColor = .white
    self.view = customView
}

Important:

• Do not call super.loadView() when overriding if you completely replace the view.
• This approach allows full control over the creation and configuration of the controller's main view.