一.NSRegularExpression

• 1.仅仅保留中文

        let str = "aiva你好94177吗??"
        
        let pattern = "[^\\u4E00-\\u9FA5]"
        
        let regex = try? NSRegularExpression(pattern: pattern, options: [])
        let result = regex?.stringByReplacingMatches(in: str, options: [],
                                                     range: NSMakeRange(0, str.count),
                                                     withTemplate: "")
        
        print(result ?? "")

• 2.常用的一些正则表达式：

非中文：[^\\u4E00-\\u9FA5]
非英文：[^A-Za-z]
非数字：[^0-9]
非中文或英文：[^A-Za-z\\u4E00-\\u9FA5]
非英文或数字：[^A-Za-z0-9]
非因为或数字或下划线：[^A-Za-z0-9_]

二. NSPredicate

        let phoneNum = "14728765642"

        let regex = "1[3456789][0-9]{9}"
        let predicate = NSPredicate(format: "SELF MATCHES %@", regex)
        let isValid = predicate.evaluate(with: phoneNum)

        print("\(isValid ? "" : "不")是手机号码")

常用的正则表达式

url

"\\b(([\\w-]+://?|www[.])[^\\s()<>]+(?:\\([\\w\\d]+\\)|([^[:punct:]\\s]|/)))"