将 UITextField 输入限制为 Swift 中的数字

Question

如何在 Swift 中将用户的 TextField 输入限制为数字？

Answer 1

第一个你必须继承你自己的 UITextViewDelegate 类 类

class ViewController: UIViewController, UITextViewDelegate {

第二次添加 IBOutlet

@IBOutlet weak var firstName: UITextField!

第三你必须确保这个对象正在使用

override func viewDidLoad() {
        super.viewDidLoad()
   firstName.delegate = self
}


func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField == firstName {
                let allowedCharacters = "1234567890"
                let allowedCharacterSet = CharacterSet(charactersIn: allowedCharacters)
                let typedCharacterSet = CharacterSet(charactersIn: string)
                let alphabet = allowedCharacterSet.isSuperset(of: typedCharacterSet)
                let Range = range.length + range.location > (fnameTF.text?.count)!

        if Range == false && alphabet == false {
            return false
        }


        let NewLength = (fnameTF.text?.count)! + string.count - range.length
        return NewLength <= 10


      } else {
        return false
    }
  }

Answer 2

对于任何寻求简短答案的人，我发现this 非常有用。

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // remove non-numerics and compare with original string
    return string == string.filter("0123456789".contains)
}

适用于 XCode 10.1、Swift 4.2

Answer 3

在 swift 4.1 和 Xcode 10 中

将 UITextFieldDelegate 添加到您的班级

class YourViewController: UIViewController, UITextFieldDelegate

然后在你的 viewDidLoad()

中编写这段代码

yourTF.delegate = self

编写此文本字段委托函数

//MARK - UITextField Delegates
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //For numers
    if textField == yourTF {
        let allowedCharacters = CharacterSet(charactersIn:"0123456789")//Here change this characters based on your requirement
        let characterSet = CharacterSet(charactersIn: string)
        return allowedCharacters.isSuperset(of: characterSet)
    }
    return true
}

Answer 4

您可以使用UITextFieldDelegate 的shouldChangeCharactersInRange 方法将用户的输入限制为数字：

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

    // Create an `NSCharacterSet` set which includes everything *but* the digits
    let inverseSet = NSCharacterSet(charactersInString:"0123456789").invertedSet

    // At every character in this "inverseSet" contained in the string,
    // split the string up into components which exclude the characters
    // in this inverse set
    let components = string.componentsSeparatedByCharactersInSet(inverseSet)

    // Rejoin these components
    let filtered = components.joinWithSeparator("")  // use join("", components) if you are using Swift 1.2

    // If the original string is equal to the filtered string, i.e. if no
    // inverse characters were present to be eliminated, the input is valid
    // and the statement returns true; else it returns false
    return string == filtered
}

---

为 Swift 3 更新：

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

    // Create an `NSCharacterSet` set which includes everything *but* the digits
    let inverseSet = NSCharacterSet(charactersIn:"0123456789").inverted

    // At every character in this "inverseSet" contained in the string,
    // split the string up into components which exclude the characters
    // in this inverse set
    let components = string.components(separatedBy: inverseSet)

    // Rejoin these components
    let filtered = components.joined(separator: "")  // use join("", components) if you are using Swift 1.2

    // If the original string is equal to the filtered string, i.e. if no
    // inverse characters were present to be eliminated, the input is valid
    // and the statement returns true; else it returns false
    return string == filtered  
}

Answer 5

iOS 没有提供这样的功能，您可以将文本字段指定为仅接受数字字符。唯一的方法是 UITextFieldDelegate 方法之一，如下所示，

(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

您需要实现以下方法并通过以下正则表达式截取输入的字符

"^([0-9]+)?(\\.([0-9]{1,2})?)?$"

或

[NSCharacterSet decimalDigitCharacterSet]

可以判断输入的字符是否为数字，如果匹配正则表达式或字符集则返回YES，否则返回NO。