检查UITextField是否仅限字符/数字

您可以简单地检查是否所有字符都满足某个条件,并检查包含有效字符的字符串是否包含这些字符。

extension StringProtocol {
    var isLetterDigitOrHyphen: Bool {
        allSatisfy("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-".contains)
    }
}

let str = "Hello"
if str.isLetterDigitOrHyphen {
    print("string is ok")
} else {
    print("string contains special characters")
}

"Hello".isLetterDigitOrHyphen  // true
"hello".isLetterDigitOrHyphen  // true
"hello1".isLetterDigitOrHyphen  // true
"hello-".isLetterDigitOrHyphen  // true

"Hello!".isLetterDigitOrHyphen  // false
"hello's".isLetterDigitOrHyphen  // false
"hello1@".isLetterDigitOrHyphen  // false
"hello$&@#".isLetterDigitOrHyphen  // false

如果要使用正则表达式:

extension StringProtocol {
    var isLetterDigitOrHyphen: Bool {
        range(of:"^[a-zA-Z0-9-]{1,}$", options: .regularExpression) != nil
    }
}

或使用字符集:

extension StringProtocol {
    var isLetterDigitOrHyphen: Bool {
        unicodeScalars.allSatisfy(CharacterSet(charactersIn: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-").contains)
    }
}

extension String {
    static let validCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-"
}

extension StringProtocol {
    var isNotLetterDigitOrHyphen: Bool {
        !unicodeScalars.allSatisfy(CharacterSet(charactersIn: .validCharacters).contains)
    }
}