Placing UIView To Cover TabBar & NavBar

Try this:

UIApplication.sharedApplication().keyWindow!.bringSubviewToFront(opaqueView)

Updating for Swift 4.2

 UIApplication.shared.keyWindow!.bringSubview(toFront: opaqueView!)

Updating for Swift 5

UIApplication.shared.keyWindow!.bringSubviewToFront(opaqueView!)

UIApplication.shared.keyWindow!.bringSubviewToFront(view: view) was depreciated after iOS 13. The best way to have your transparent view cover both the tab controller and nav controller is by doing this.

if let tabBarController = self.tabBarController {
    tabBarController.view.addSubview(view)
}