Question

我想让textField只接受小字母而非大写字母或没有任何特殊符号或不接受任何数字。

Answer 1

您可以使用正则表达式，例如下面只允许使用小符号的正则表达式

{{1}}

Answer 2

限制大写字母，数字和＆amp;特殊符号，在文本视图委托方法false中以小写字母返回textField:shouldChangeCharactersInRange:。

Swift 3.0：

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        var myCharSet = CharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyz")
        for i in 0..<(string.characters.count ?? 0) {
            var c: unichar = string[i]
            if !myCharSet.characterIsMember(c) {
                return false
            }
        }
        return true
    }

Answer 3

检查此更新的代码：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    NSLog(@"textField:shouldChangeCharactersInRange:replacementString:");
         NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyz"];
        for (int i = 0; i < [string length]; i++)
        {
            unichar c = [string characterAtIndex:i];
            if (![myCharSet characterIsMember:c])
            {
                return NO;
            }
        }

        return YES;
    }

}

在Swift中

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

        let set = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyz").invertedSet
        return string.rangeOfCharacterFromSet(set) == nil

    }

Answer 4

请尝试以下代码，仅自动获取小写字母。

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var textEntry: UITextField!

   //MARK : - Life Cycle
    override func viewDidLoad() {
        super.viewDidLoad()
       textEntry.addTarget(self, action: #selector(self.textFieldDidChange), for: .editingChanged)
    }

    //MARK: - Lower letter function
    func textFieldDidChange(sender: UITextField) {
        sender.text = sender.text?.lowercased()
        print(textEntry.text ?? "") //Check your text output here
    }
 }

Answer 5

您也可以使用它，

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

    // Return false when user tries to delete but textField is empty
    let currentCharacterCount = textField.text?.characters.count ?? 0
    if (range.length + range.location > currentCharacterCount) {
        return false
    }

    // Return true when user tries to delete but textField is not empty
    if string == "" {
        return true
    }

    let userEnteredString = textField.text ?? ""
    let newString = (userEnteredString as NSString).replacingCharacters(in: range, with: string) as NSString

    return ((newString as String).range(of: "^[a-z]+$", options: .regularExpression) != nil)

}

Answer 6

您必须使用自己的类继承UITextFieldDelegate类

class ViewController: UIViewController, UITextFieldDelegate {
添加IBOutlet

@IBOutlet weak var firstName: UITextField!

您必须确保该对象正在使用

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

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField == firstName {
        let allowedCharacters = "abcdefghijklmnopqrstuvwxyz"
        let allowedCharacterSet = CharacterSet(charactersIn: allowedCharacters)
        let typedCharacterSet = CharacterSet(charactersIn: string)
        let alphabet = allowedCharacterSet.isSuperset(of: typedCharacterSet)
        return alphabet
    }
}

让UITextField只接受Swift中的小字母？

6 个答案: