String Essentials

Evolution Discussion
15

Another example use for offsetting an index, from @Ray_Fix's post

  mutating func appendInterpolation<T: BinaryFloatingPoint>(_ value: T, precision: Int = 3) {
    var result = String(describing: value)
    defer { appendInterpolation(result) }

    guard precision > 0 else { return }

    let string = result
    guard let index = string.firstIndex(of: ".") else { return }

    let offset = precision+1
    let last = string.index(index, offsetBy: offset,
                            limitedBy: string.endIndex) ?? string.endIndex

    result = String(string[..<last])

    let fraction = string[index..<last].count

    if fraction < offset {
      result += String(repeating: "0", count: offset-fraction)
    }
  }