表达式类型'(_,_ .tride) - > _'是不明确的,没有更多的上下文

Question

救命!我遇到错误'表达式类型'(_,_.Stride) - > _'是不明确的,没有更多的上下文'.有谁知道为什么会这样,并有解决方案吗？我使用的是Swift 4.
代码:

let offsetTime = 0
DispatchQueue.main.asyncAfter(deadline: .now() + offsetTime) { //Expression type '(_, _.Stride) -> _' is ambiguous without more context
    self.currentTaskForUser.text = "Starting\n" + note +  "in"
    self.timerDown(from: 3, to: 1)
}
DispatchQueue.main.asyncAfter(deadline: .now() + offsetTime + 3) { //Expression type '(_, _.Stride) -> _' is ambiguous without more context
    self.currentTaskForUser.text = note
    let difficultyValue = Int(self.difficultyControl.titleForSegment(at: self.difficultyLevel.selectedSegmentIndex)!)!
    self.timerUp(from: 1, to: difficultyValue)
    self.offsetTime += 13
}

Answer 1

表达式.now()返回DispatchTime一个结构类型.

let offsetTime = 0将变量初始化为Int.该错误具有误导性,实际上它是一种类型不匹配

虽然编译器可以推断出数字文字的类型

DispatchQueue.main.asyncAfter(deadline: .now() + 3)

向Int文本或变量添加DispatchTime值的最可靠方法是DispatchTimeInterval具有关联值的情况.

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(offsetTime)

和

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(offsetTime) + .seconds(3))

有四个DispatchTimeInterval枚举案例

• .seconds(Int)
• .milliseconds(Int)
• .microseconds(Int)
• .nanoseconds(Int)