Приведение указателей к _Атомным указателям и _Атомным размерам

Swift 4

extension UIView {

func fadeIn(duration: TimeInterval = 0.5, delay: TimeInterval = 0.0, completion: @escaping ((Bool) -> Void) = {(finished: Bool) -> Void in }) {
    self.alpha = 0.0

    UIView.animate(withDuration: duration, delay: delay, options: UIViewAnimationOptions.curveEaseIn, animations: {
        self.isHidden = false
        self.alpha = 1.0
    }, completion: completion)
}

func fadeOut(duration: TimeInterval = 0.5, delay: TimeInterval = 0.0, completion: @escaping (Bool) -> Void = {(finished: Bool) -> Void in }) {
    self.alpha = 1.0

    UIView.animate(withDuration: duration, delay: delay, options: UIViewAnimationOptions.curveEaseIn, animations: {
        self.alpha = 0.0
    }) { (completed) in
        self.isHidden = true
        completion(true)
    }
}
}

И чтобы использовать его, просто вызовите следующие функции:

yourView.fadeOut() // this will hide your view with animation
yourView.fadeIn() /// this will show your view with animation