Question

我试图了解如何使用UIView.animateKeyframes，但是我一生都无法理解如何计算时间/持续时间。

我正在努力实现以下目标：我希望整个动画持续10秒钟，由...组成。

第一个addKeyframe运行时间为01秒，耗时1秒

second addKeyframe在02秒运行，耗时1秒

第三个addKeyframe运行时间为05秒，耗时2秒

第四个addKeyframe的运行时间为07秒，耗时1秒

第四个addKeyframe的运行时间为09秒，耗时1秒

  fileprivate func animateWelcomeText() -> Void {

        let duration: TimeInterval = 10

        UIView.animateKeyframes(withDuration: duration, delay: 0, options: .calculationModeLinear, animations: {
            UIView.addKeyframe(withRelativeStartTime: 1.0, relativeDuration: 1.0, animations: {
                self.introTextLabel.alpha = 1
            })

            UIView.addKeyframe(withRelativeStartTime: 2.0, relativeDuration: 1.0, animations: {
                self.introTextLabelTwo.alpha = 1
            })

            UIView.addKeyframe(withRelativeStartTime: 5.0, relativeDuration: 2.0, animations: {
                self.introTextLabel.alpha = 0
                self.introTextLabelTwo.alpha = 0
            })

            UIView.addKeyframe(withRelativeStartTime: 7.0, relativeDuration: 1.0, animations: {
                self.introTextLabelThree.alpha = 1
            })

            UIView.addKeyframe(withRelativeStartTime: 9.0, relativeDuration: 1.0, animations: {
                self.introTextLabelFour.alpha = 1
            })

        }) { (_) in
            print("Complete")
        }
    }

什么也没发生，然后动画完成，最后两个项目突然出现。

Answer 1

这只是数学。只需将所有值除以持续时间即可获得相对值。

fileprivate func animateWelcomeText() -> Void {

    let duration: TimeInterval = 10

    UIView.animateKeyframes(withDuration: duration, delay: 0, options: .calculationModeLinear, animations: {
        UIView.addKeyframe(withRelativeStartTime: 1/duration, relativeDuration: 1/duration, animations: {
            self.introTextLabel.alpha = 1
        })
        UIView.addKeyframe(withRelativeStartTime: 2/duration, relativeDuration: 1/duration, animations: {
            self.introTextLabelTwo.alpha = 1
        })
        UIView.addKeyframe(withRelativeStartTime: 5/duration, relativeDuration: 2/duration, animations: {
            self.introTextLabel.alpha = 0
            self.introTextLabelTwo.alpha = 0
        })

        UIView.addKeyframe(withRelativeStartTime: 7/duration, relativeDuration: 1/duration, animations: {
            self.introTextLabelThree.alpha = 1
        })

        UIView.addKeyframe(withRelativeStartTime: 9/duration, relativeDuration: 1/duration, animations: {
            self.introTextLabelFour.alpha = 1
        })

    }) { (_) in
        print("Complete")
    }
}

您的值不等于x（10）。该方法需要1。

如何在animateKeyframes中计算relativeDuration

1 个答案: