title: Add New Window and make it key window in SWIFTUI
body: <p>I want to add a new window as I want to create a a full screen loader. I have tried to add a new window in and set that as rootviewcontroller. But it is not adding into the windows hierarchy. Below is my code. I am learning swiftUI. Any help is appreciated. </p>
  
  <pre><code>let window = UIWindow()
  window.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
  window.backgroundColor = .blue
  window.isHidden = false
  window.rootViewController = UIHostingController(rootView: Text("Loading...."))
  window.makeKeyAndVisible()
  </code></pre>