Animations of FadeIn / FadeOut

UIView+Fade.swift

// Modified from: https://qiita.com/mono0926/items/c53b2e46e51a0b0bbf06
enum FadeType: TimeInterval {
    case normal = 0.2
    case slow = 1.0
}

extension UIView {

    func fadeIn(_ type: FadeType = .normal, completion: (() -> Void)? = nil) {
        self.alpha = 0
        self.isHidden = false
        UIView.animate(withDuration: type.rawValue, animations: {
            self.alpha = 1
        }, completion: { _ in
            completion?()
        })
    }

    func fadeOut(type: FadeType = .normal, completion: (() -> Void)? = nil) {
        UIView.animate(withDuration: type.rawValue, animations: {
            self.alpha = 0
        }, completion: { [weak self] _ in
            self?.isHidden = true
            self?.alpha = 1
            completion?()
        })
    }
}