ios - Swift4 将特定字符串转换为特定 Int

Question

喜欢我的问题标题。
如果我得到 A，我想返回 0。
如果我得到 B，我想返回 1。
....
如果我得到 Z，我想返回 25。
如何让这个功能看起来更好更简单？谢谢。

func convertStringToInt(text: String) -> Int {

 switch text {
    case "A":
        return 0
    case "B":
        return 1

    //...C TO Y

    case "Z":
        return 25
    default:
        break
    }
    return 0

}

Answer 1

使用 ASCII 值，您可以将其缩短为(也适用于小写):

func convertStringToInt(characterText: String) -> Int? {
    guard let aValue = "A".unicodeScalars.first?.value,
        let zValue = "Z".unicodeScalars.first?.value,
        let characterValue = characterText.uppercased().unicodeScalars.first?.value,
        // next line tests if the input value is between A and Z
        characterValue >= aValue && characterValue <= zValue else {
            return nil // error

    }
    return Int(characterValue) - Int(aValue)
}

print("Value for A: \(convertStringToInt(characterText: "A"))")
print("Value for G: \(convertStringToInt(characterText: "G"))")
print("Value for Z: \(convertStringToInt(characterText: "Z"))")
print("Value for z: \(convertStringToInt(characterText: "z"))")
print("Value for ^: \(convertStringToInt(characterText: "^"))")

打印:

Value for A: Optional(0)
Value for G: Optional(6)
Value for Z: Optional(25)
Value for z: Optional(25)
Value for ^: nil

基于 this question .

或者，如果您想使用数组索引:

func convertStringToInt(characterText: String) -> Int {
    let array = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
    return array.firstIndex(of: characterText.uppercased()) ?? -1 // default value for a text that is not found
}