元组 Void (aka ()) 的值没有成员“isSuperset”

Question

我在两个字符集之间创建了一个联合，以便能够将句点与 decimalDigits 字符集一起使用。

 func textField(_ textField: UITextField, shouldChangeCharactersIn     range: NSRange, replacementString string: String) -> Bool {

            let allowed = CharacterSet.decimalDigits
            let period = CharacterSet.init(charactersIn: ".")
            let both = CFCharacterSetUnion(allowed as! CFMutableCharacterSet, period as CFCharacterSet)

            let characterSet = NSCharacterSet(charactersIn: string)

            return both.isSuperset(of: characterSet as CharacterSet)
        }

但是，返回“both.isSuperset(of: characterSet as CharacterSet)”。如何纠正？

更新 1： 当前建议的答案显示的错误

更新 2： 最近更新

Answer 1

尝试这样做：

func textField(_ textField: UITextField, shouldChangeCharactersIn     range: NSRange, replacementString string: String) -> Bool {

    var allowed = CharacterSet.decimalDigits
    let period = CharacterSet.init(charactersIn: ".")
    allowed.formUnion(period)

    //UNCOMMENT when isSuperset is working
    //let characterSet = CharacterSet(charactersIn: string)
    //return allowed.isSuperset(of: characterSet)

    // Swift 3 appropriate solution 
    let isSuperset = string.rangeOfCharacter(from: allowed.inverted) == nil
    return isSuperset
}

I found here 的依据。

更好的是，将“allowed”（或“both”，无论您决定如何命名）设置为在viewDidLoad 中创建的属性，这样您就不必每次都重新创建和合并字符集字符被键入。