In what cases is it necessary to override or change the loadView method in iOS applications?

The loadView method in iOS is overridden when you need to create a custom user interface programmatically, without using Storyboard or XIB. By default, loadView loads the view from a nib file or Storyboard. If you want to have full control over the creation of the root view controller, you should override this method and assign your view to the self.view property.

Example of overriding:

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

This is useful when the interface is created dynamically or in projects without using Interface Builder.