Swift3.0无法转换&#39;ClosedRange类型的值 <Index> &#39;输入&#39;范围 <Index> “

Question

我正在尝试将Swift 2.3迁移到3.0并在转换后面临此问题。 有什么建议我做错了。

Swift 3.0：

override func setValue(_ value: AnyObject?, forKey key: String) {
    let uppercasedFirstCharacter = String(key.characters.first!).uppercased()
    let range = key.startIndex...key.index(key.startIndex, offsetBy: 0)
    let selectorString = key.replacingCharacters(in: range, with: uppercasedFirstCharacter)

    let selector = NSSelectorFromString("set\(selectorString):")
    let responds = self.responds(to: selector)

    if !responds {
        return
    }

错误：

let selectorString = key.replacingCharacters（in：range，with：uppercasedFirstCharacter）

 Cannot convert value of type 'ClosedRange<Index>' (aka 'ClosedRange<String.CharacterView.Index>') to expected argument type 'Range<Index>' (aka 'Range<String.CharacterView.Index>') 

原始代码：Swift 2.3

override func setValue(value: AnyObject?, forKey key: String) {
    let uppercasedFirstCharacter = String(key.characters.first!).uppercaseString

    let range = key.startIndex...key.startIndex.advancedBy(0)
    let selectorString = key.stringByReplacingCharactersInRange(range, withString: uppercasedFirstCharacter)

    let selector = NSSelectorFromString("set\(selectorString):")
    let responds = self.respondsToSelector(selector)

    if !responds {
        return
    }

Answer 1

您可以使用..<而不是... for range为Range<Index>类型而不是ClosedRange<Index> ，在这种情况下，对stringByReplacingCharactersInRange(...)的调用不会产生错误（请注意offsetBy增加1 ）。

let range = key.startIndex..<key.index(key.startIndex, offsetBy: 1)
// range is now type Range<Index>

现在，我可能错了，但似乎你只是想让selectorString成为第一个字符大写的key的版本。 您的范围解决方案的另一种方法是，例如，使用String扩展解决方案，如下所示：

extension String { 
   var firstCharacterUppercased: String {
        guard case let c = self.characters,
                   let c1 = c.first else { return self }
        return String(c1).uppercased() + String(c.dropFirst())
    }
}

/* example usage */
let key = "fooBar"
let selectorString = key.firstCharacterUppercased

print(selectorString) // FooBar

Answer 2

Swift 3+

override func setValue(_ value: Any?, forKey key: String) {
        let upperCaseFirstCharacter = String(key.characters.first!).uppercased()
        let range = key.startIndex..<key.index(key.startIndex, offsetBy: 1)
        let selectorString = key.replacingCharacters(in: range, with: upperCaseFirstCharacter)

        let selector = NSSelectorFromString("set\(selectorString):")
        let responds = self.responds(to: selector)

        if !responds{
            return
        }
        super.setValue(value, forKey: key)
    }

    init(dictionary: [String: Any]){
        super.init()
        setValuesForKeys(dictionary)
    }