IOS仿京東收藏心跳動畫

最近在看IOS動畫相關的東西，正好看到京東收藏商品的時候有個心跳的動畫，于是研究了一下，代碼很簡單

let heart = UIButton(frame: CGRect(x: APP_FRAME_WIDTH*0.5-25, y: 200, width: 50, height: 50))
        self.view.addSubview(heart)
        heart.setImage(UIImage(named: "heart") , for: .normal)
        heart.setImage(UIImage(named: "hearted") , for: .selected)
        heart.addTarget(self, action: #selector(ViewController.click(_:)), for: .touchUpInside)

點擊事件：

button.isSelected = !button.isSelected
        let k = CAKeyframeAnimation.init(keyPath: "transform.scale")
        k.values = [0.1,1.0,1.5]
        k.keyTimes = [0.0,0.8,1.0]
        k.calculationMode = kCAAnimationLinear
        button.layer.add(k, forKey: "SHOW")

來自：http://www.jianshu.com/p/4f0f5ea0d17a