Swift中的延迟动作 [英] Delay Actions in Swift

问题描述

我想让活动指示器开始动画，然后在一秒钟后停止。

I want to make an Activity Indicator start animating and then stop after one second.

那么有人知道我该怎么做吗？

So does anyone know how I could do that?

class stuff {
@IBOutlet weak var indicator: UIActivityIndicatorView!

   func iGotTriggeredBySomething {
      indicator.startAimating()
      //delay?
      indicator.stopAnimating()
   }
}

感谢

推荐答案

dispatch_after（）是延迟动作的标准方法

dispatch_after() is the standard way of delaying actions.

indicator.startAnimating()

let delay = 4.5 * Double(NSEC_PER_SEC)
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
dispatch_after(time, dispatch_get_main_queue()) {
    indicator.stopAnimating()
}

请参阅： dispatch_after -快速启动GCD吗？

为Swift 3.0更新

indicator.startAnimating()

let delay = Int(4.5 * Double(1000))
DispatchQueue.main.after(when: .now() + .milliseconds(delay)) {
    indicator.stopAnimating()
}

但是，本着Swift 3.0的精神，我认为扩展 DispatchQueue 是一个更好的解决方案。

However, in the spirit of Swift 3.0, I think extending DispatchQueue would be a better solution.

extension DispatchQueue {
    func delay(_ timeInterval: TimeInterval, execute work: () -> Void) {
        let milliseconds = Int(timeInterval * Double(1000))
        after(when: .now() + .milliseconds(milliseconds), execute: work)
    }
}

这给我们留下了很好的印象

This leaves us with a very nice

indicator.startAnimating()

DispatchQueue.main.delay(4.5) {
    indicator.stopAnimating()
}

---

更新2

深入到Xcode 8.0 beta，我发现 public func +（time：DispatchTime，seconds：Double）-> DispatchTime 。所以，我想这是正确的……

Digging into the Xcode 8.0 beta, I found public func +(time: DispatchTime, seconds: Double) -> DispatchTime. So, I guess this is valid…

indicator.startAnimating()

DispatchQueue.main.after(when: .now() + 4.5) {
    indicator.stopAnimating()
}

我认为没有必要为已经很干净的东西扩展 DispatchQueue 。

I don't think there is a need to extend DispatchQueue for something this clean already.

-

Swift 3.1更新

Update for Swift 3.1

Swift 3.1有新的语法。他们只是喜欢改变事物而已。

There is new syntax for Swift 3.1. They just likes to change things don't they.

indicator.startAnimating()

DispatchQueue.main.asyncAfter(deadline: .now() + 4.5) {
    indicator.stopAnimating()
}

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