延时循环调用动画过程

Question

这是我的一段代码，我在其中尝试延迟一个名为 dropText 的函数，该函数从屏幕顶部删除一个名称。我尝试使用延迟功能，但它会延迟然后立即将它们全部删除。我错过了什么，或者这种方法完全错误？提前致谢：

func delay(_ delay:Double, closure:@escaping ()->()) {
    DispatchQueue.main.asyncAfter(
        deadline: DispatchTime.now() + Double(Int64(delay * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC), execute: closure)
}

//New group choose method
func groupChoose()
{
    //loop through the players
    for x in 0...players - 1{
            //drop the name in from the top of the screen
            delay(2.0) {
            self.dropText(playing[x])
    }
}

Answer 1

这个问题是因为你一次拖延了所有的人！您应该尝试为每个分配不同的延迟时间：

for x in 1...players {
   //drop the name in from the top of the screen
   delay(2.0 * x) {
   self.dropText(playing[x-1])
}

重构

尽量不要按索引调用数组元素：

for playing in playing.enumerated() {
// drop the name in from the top of the screen
let player = playing.offset + 1
delay(2.0 * player) {
    self.dropText(playing.element)
}

Answer 2

看看循环。您几乎立即一个接一个地呼叫 asyncAfter。所以文本在延迟后 几乎立即一个接一个 也被丢弃。

我建议使用 Timer

func delay(_ delay: Double, numberOfIterations: Int, closure:@escaping (Int) -> Void) {
    var counter = 0
    Timer.scheduledTimer(withTimeInterval: delay, repeats: true) { timer in
        DispatchQueue.main.async { closure(counter-1) }
        counter += 1
        if counter == numberOfIterations { timer.invalidate() }
    }
}

和

func groupChoose()
{
    delay(2.0, numberOfIterations: players) { counter in
         self.dropText(playing[counter])
    }
}

延时循环调用动画过程

Delay loop calling animation process

xcode

delay

swift

重构