我该如何使用阿尔法扩展对于SWIFT所有的对象？

Question

我有下面的代码改变，如文本，图像，...与影响对象的值。和它的工作：

UIView.animate(withDuration: 1.0, delay: 0.0, options: UIViewAnimationOptions.curveEaseOut, animations: {
                        self.lblCityTemp.alpha = 0.0
                        self.imgCityIcon.alpha = 0.0
                    }, completion: {
                        (finished: Bool) -> Void in

                        //Once the label is completely invisible, set the text and fade it back in
                        self.imgCityIcon.image = UIImage(named: icon)
                        self.lblCityTemp.text = "\(temp)°"

                        // Fade in
                        UIView.animate(withDuration: 1.0, delay: 0.0, options: UIViewAnimationOptions.curveEaseIn, animations: {
                            self.lblCityTemp.alpha = 1.0
                            self.imgCityIcon.alpha = 1.0

                        }, completion: nil)
                    })

现在，我希望做一个扩展的代码，我用我所有的对象，我下面写的代码：

extension NSObject {

    func Fade (alphaOUT: Double,alphaIN: Double, input: Any) {
        UIView.animate(withDuration: 1.0, delay: 0.0, options: UIViewAnimationOptions.curveEaseOut, animations: {
            self.alpha = CGFloat(alphaOUT)
        }, completion: {
            (finished: Bool) -> Void in

            // Fade in
            UIView.animate(withDuration: 1.0, delay: 0.0, options: UIViewAnimationOptions.curveEaseIn, animations: {
                self.alpha = CGFloat(alphaIN)

            }, completion: nil)
        })
    }
}

但是我有自我字错误，我不知道我怎么能像标签，ImageView的，每个对象的设定值....

我怎样才能做到这一点？是扩展是最好的办法还是没有？如果没有，那么，什么是最好的方式？

Answer 1

整个想法应该采取一些UIView和动画它。然后，你需要UIView的扩展，因为这个类有你需要的属性。

extension UIView { ... }

无论如何，如果你需要什么现在当动画结束时做一些事情？然后，你需要完成处理程序参数的方法

func fade(..., completion: @escaping () -> Void = { }) {

......第一动画结束后会被调用。

下一步建议：

• 可以说，阿尔法参数的类型应该CGFloat的，那么你就不必转换Double到CGFloat
• 此外，什么是input？我想你不会有这种解决方案需要它
• 方法名称应与小大写字母开头和命名参数，你应该使用驼峰

---

extension UIView {
    func fade(alphaOut: CGFloat, alphaIn: CGFloat, completion: @escaping () -> Void = { }) {
        UIView.animate(withDuration: 1, delay: 0, options: .curveEaseOut, animations: {
            self.alpha = alphaOut
        }, completion: { _ in
            completion() // this is called when animation ends
            UIView.animate(withDuration: 1, delay: 0, options: .curveEaseIn, animations: {
                self.alpha = alphaIn
            })
        })
    }
}

然后，当你需要调用它，改变你需要什么completion关闭动画结束后，

imgCityIcon.fade(alphaOut: ___, alphaIn: ___) {
    self.imgCityIcon.image = UIImage(named: icon)
}

---

请注意，您在使用旧语法的一些东西：

例如UIViewAnimationOptions.curveEaseIn已更名为UIView.AnimationOptions.curveEaseIn。我建议你开始使用雨燕的新版本

Answer 2

您需要实现UIView而不是NSObject的一个扩展。因为NSObject的没有像阿尔法任何财产，你会得到一个错误。

编码实施例：

extension UIView {
    func Fade (alphaOUT: Double,alphaIN: Double, input: Any) {
        UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseOut, animations: {
            self.alpha = CGFloat(alphaOUT)
        }, completion: {
            (finished: Bool) -> Void in

            // Fade in
            UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseIn, animations: {
                self.alpha = CGFloat(alphaIN)

            }, completion: nil)
        })
    }
}

class AnimationHelper {

class func Fade (alphaOUT: Double,alphaIN: Double, input: Any , yourLabel: UILabel, yourTextField: UITextField) {
            UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseOut, animations: {
                yourLabel.alpha = CGFloat(alphaOUT)
                yourTextField.alpha = CGFloat(alphaOUT)
            }, completion: {
                (finished: Bool) -> Void in

                // Fade in
                UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseIn, animations: {
                    // Access your text field and label here.

                }, completion: nil)
            })
        }

}