如何转换 ClosedRange<int> 到 ClosedRange<double> 在 Swift</double></int>

Question

我有一个 ClosedRange 作为参数传入，现在我需要将它转换为 ClosedRange：

  let range: ClosedRange<Int>
  
  init(range: ClosedRange<Int>) {
    self.range = range
  }


  var body: some View {
    Slider(value: doubleBinding, in: range.startIndex...range.endIndex, step: 1)
  }

Slider init function 采用 ClosedRange 参数。 所以我得到了这个错误：

Cannot convert value of type 'ClosedRange<Int>.Index' to expected argument type 'Double'

所以我尝试了这个：

  let min = Double(Int(range.startIndex))
  let max = Double(Int(range.endIndex))
  Slider(value: doubleBinding, in: min...max, step: 1)

但是得到这个错误：

Initializer 'init(_:)' requires that 'ClosedRange<Int>.Index' conform to 'BinaryInteger'

Answer 1

您使用了错误的属性。 它不是startIndex和endIndex 。 它是lowerBound和upperBound ：

Slider(value: doubleBinding, 
       in: Double(range.lowerBound)...Double(range.upperBound), 
       step: 1)

您可以编写一个ClosedRange初始化程序来方便地执行此操作：

extension ClosedRange {
    init<Other: Comparable>(_ other: ClosedRange<Other>, _ transform: (Other) -> Bound) {
        self = transform(other.lowerBound)...transform(other.upperBound)
    }
}

用法：

Slider(value: doubleBinding, 
       in: ClosedRange(range, Double.init), 
       step: 1)