Question

我是UI编程的新手，现在我正试图根据屏幕点击的次数来制作屏幕脉冲。我的问题是，当检测到点击并缩短动画的持续时间时，它会从头开始动画，在重新启动时创建白色闪光。如何在检测到水龙头的任何时刻开始加速动画。

我的代码：

class ViewController: UIViewController {

    var tapCount: Int = 0
    var pulseSpeed: Double = 3

    override func viewDidLoad() {
        super.viewDidLoad()

        counter.center = CGPoint(x: 185, y: 118)

        pulseAnimation(pulseSpeed: pulseSpeed)
    }

    func pulseAnimation(pulseSpeed: Double) {
        UIView.animate(withDuration: pulseSpeed, delay: 0, options:   [UIViewAnimationOptions.repeat, UIViewAnimationOptions.autoreverse],
        animations: {
            self.red.alpha = 0.5
            self.red.alpha = 1.0
        })
    }

    @IBOutlet weak var red: UIImageView!
    @IBOutlet weak var counter: UILabel!

    @IBAction func screenTapButton(_ sender: UIButton) {
        tapCount += 1
        counter.text = "\(tapCount)"
        pulseSpeed = Double(3) / Double(tapCount)
        pulseAnimation(pulseSpeed: pulseSpeed)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

    }

}

Answer 1

您需要直接使用Core Animation来实现您所追求的目标，而不是依赖于内置于顶层的UIView动画。

// create animation in viewDidLoad
let pulseAnimation = CABasicAnimation(keyPath: "opacity")
pulseAnimation.fromValue = 0.5
pulseAnimation.toValue = 1.0
pulseAnimation.autoreverses = true
pulseAnimation.duration = 3.0
pulseAnimation.repeatCount = .greatestFiniteMagnitude

// save animation to property on ViewController
self.pulseAnimation = pulseAnimation

// update animation speed in screenTapButton
pulseAnimation.speed += 0.5

您可能想稍微使用速度数字。默认速度为1.0，动画指定持续时间为3秒，因此从0.5到1.0需要6秒才能恢复到0.5。在2.0的速度下，相同的动画将快速发生两次，或者整个周期发生3秒。

我希望有所帮助！

如何在使用swift进行动画时加快动画效果？

1 个答案: