参数是未声明的类型？

Question

我正在尝试为函数设置参数，但控制台显示

使用未声明的类型rightAnimation

func slideFromRight(from: rightInAnimation.fromValue = 25) {

    let rightInAnimation = CABasicAnimation(keyPath: "transform.translation.x")
    rightInAnimation.duration = 0.5
    rightInAnimation.fromValue = 25
    rightInAnimation.toValue = 0
    rightInAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

    self.layer.add(rightInAnimation, forKey: "animateTranslation")
}

我很困惑。我以为我不必在顶层声明这一点。目的是在分配时能够更改fromValue。

Answer 1

问题在于以下代码：

func slideFromRight(from: rightInAnimation.fromValue = 25)

您需要将其更改为：

func slideFromRight(from : Int = 25)
{
    let rightInAnimation            = CABasicAnimation(keyPath: "transform.translation.x")
    rightInAnimation.duration       = 0.5
    rightInAnimation.fromValue      = from
    rightInAnimation.toValue        = 0
    rightInAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

    self.layer.add(rightInAnimation, forKey: "animateTranslation")
}