覆盖UIImageView的图像getter/setter方法

Question

我正在为UIImageView创建子类,因此每次设置图像属性时都会发生动画.以下是成功的:

import UIKit

class AnimatedImageView: UIImageView {

var img: UIImage! {
    get {
        return self.image
    }
    set {
        self.image = newValue

        UIView.animateWithDuration(0.5, delay: 0.4, usingSpringWithDamping: 0.2, initialSpringVelocity: 5.0, options: .CurveEaseIn, animations: {_ in

            self.transform = CGAffineTransformMakeScale(1.1, 1.1);

            }, completion: {_ in
                self.transform = CGAffineTransformIdentity;
        })
    }
}

这并不奇怪.我将UIImageView子类化并添加了一个名为'img'的全新变量,该变量又修改了UIImageView的'image'属性.

问题是最终用户可能会改变AnimatedImageView的'image'属性.

import UIKit

class AnimatedImageView: UIImageView {

override var image: UIImage! {
 get {
     return self.image
 }
 set {
    self.image = newValue

    UIView.animateWithDuration(0.5, delay: 0.4, usingSpringWithDamping: 0.2, initialSpringVelocity: 5.0, options: .CurveEaseIn, animations: {_ in

        self.transform = CGAffineTransformMakeScale(1.1, 1.1);

        }, completion: {_ in
            self.transform = CGAffineTransformIdentity;
    })
 }
}

果然这会导致堆栈溢出,因为当我self.image = newValue重复调用它时,会调用我在子类中重写的setter方法.那么,在UIImageView上覆盖'image'属性的getter/setter方法的正确方法是什么

Answer 1

只需使用super.image,这将阻止循环.