swift - 错误: Cannot convert value of type 'UInt64' to expected argument type 'DispatchTime'

Question

我试图在 Swift4 中创建一个由变量控制的计时器，唯一的问题是我收到错误:

Cannot convert value of type 'UInt64' to expected argument type 'DispatchTime'

这是代码:

let maxNumber = maxNumberField.intValue
let amountOfNumbers = amountOfNumbersField.intValue
var delay = 5
var x: Int32 = amountOfNumbers

while(x > 0){

    let when = (DispatchTime.now().uptimeNanoseconds + (5 * UInt64(x)))
    DispatchQueue.main.asyncAfter(deadline: when) { // error

        let number = arc4random_uniform(UInt32(maxNumber + 1))
        let synth = NSSpeechSynthesizer()
        synth.startSpeaking(String(number))
    }
    x = (x - 1)
}

根据我的理解，我需要将 when 变量(UInt64)转换为 DispatchTime。

我该怎么做？

Answer 1

您应该:

• 使用DispatchTime.init(uptimeNanoseconds:)与您的 when 变量。

• 使用这个:let when = (DispatchTime.now() + (5 * Double(x)))，因为 + 重载 (DispatchTime, Double).