swift UITextField限制

• 限制小数点后面2位

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    
    guard let text = textField.text else {
        return true
    }
    
    //新输入的
    if string.count == 0 {
        return true
    }
    
    //判断新的文本内容是否符合要求
    return isValid(text: text, replacementString: string, range: range)
}

///检测改变过的文本是否匹配正则表达式，如果匹配表示可以键入，否则不能键入
func isValid(text: String, replacementString string: String, range: NSRange) -> Bool {
    
    //第一个参数，被替换字符串的range
    //第二个参数，即将键入或者粘贴的string
    //返回的是改变过后的新str，即textfield的新的文本内容
    let checkStr = (text as NSString).replacingCharacters(in: range, with: string)
    
    //正则表达式（只支持两位小数）
    let regex = "^\\-?([1-9]\\d*|0)(\\.\\d{0,2})?$"
    let predicte = NSPredicate(format:"SELF MATCHES %@", regex)
    return predicte.evaluate(with: checkStr)
}

• 限制11位手机号

fileprivate func validateNumber(_ textField: UITextField, range: NSRange, string: String, limit: Int = 11) -> Bool {
    
    guard let text = textField.text else { return false }

    ///拼接了参数string的afterStr
//        let afterStr = text.replacingCharacters(in: text.ext2Range(range)!, with: string)
//        DebugLog(afterStr)
    let afterStr = (text as NSString).replacingCharacters(in: range, with: string)
    DebugLog(afterStr)
    
    ///限制长度
    if afterStr.count > limit {
        textField.text = (afterStr as NSString).substring(to: limit)
        return false
    }
    
    ///是否都是数字
    let set = CharacterSet(charactersIn: "0123456789").inverted
    let filteredStr = string.components(separatedBy: set).joined(separator: "")
    
    if filteredStr == string {
        return true
    }
    
    return false
}