UITextField 只允许字母数字字符

Question

如何在 iOS UITextField 中只允许输入字母数字字符？

Answer 1

将 UITextFieldDelegate 方法 -textField:shouldChangeCharactersInRange:replacementString: 与 NSCharacterSet 一起使用，其中包含您要允许的字符的反转。例如：

// in -init, -initWithNibName:bundle:, or similar
NSCharacterSet *blockedCharacters = [[[NSCharacterSet alphanumericCharacterSet] invertedSet] retain];

- (BOOL)textField:(UITextField *)field shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)characters
{
    return ([characters rangeOfCharacterFromSet:blockedCharacters].location == NSNotFound);
}

// in -dealloc
[blockedCharacters release];

请注意，您需要声明您的类实现了协议（即@interface MyClass : SomeSuperclass <UITextFieldDelegate>）并将文本字段的delegate 设置为您的类的实例。

Answer 2

Swift 3 版本

目前接受的回答方式：

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

    // Get invalid characters
    let invalidChars = NSCharacterSet.alphanumerics.inverted

    // Attempt to find the range of invalid characters in the input string. This returns an optional.
    let range = string.rangeOfCharacter(from: invalidChars)

    if range != nil {
        // We have found an invalid character, don't allow the change
        return false
    } else {
        // No invalid character, allow the change
        return true
    }
}

另一种功能相同的方法：

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

    // Get invalid characters
    let invalidChars = NSCharacterSet.alphanumerics.inverted

    // Make new string with invalid characters trimmed
    let newString = string.trimmingCharacters(in: invalidChars)

    if newString.characters.count < string.characters.count {
        // If there are less characters than we started with after trimming
        // this means there was an invalid character in the input. 
        // Don't let the change go through
        return false
    } else {
        // Otherwise let the change go through
        return true
    }

}

Answer 3

这就是我的做法：

// Define some constants:
#define ALPHA                   @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
#define NUMERIC                 @"1234567890"
#define ALPHA_NUMERIC           ALPHA NUMERIC

// Make sure you are the text fields 'delegate', then this will get called before text gets changed.
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    // This will be the character set of characters I do not want in my text field.  Then if the replacement string contains any of the characters, return NO so that the text does not change.
    NSCharacterSet *unacceptedInput = nil;

    // I have 4 types of textFields in my view, each one needs to deny a specific set of characters:
    if (textField == emailField) {
        //  Validating an email address doesnt work 100% yet, but I am working on it....  The rest work great!
        if ([[textField.text componentsSeparatedByString:@"@"] count] > 1) {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@".-"]] invertedSet];
        } else {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@".!#$%&'*+-/=?^_`{|}~@"]] invertedSet];
        }
    } else if (textField == phoneField) {
        unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMERIC] invertedSet];
    } else if (textField == fNameField || textField == lNameField) {
        unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:ALPHA] invertedSet];
    } else {
        unacceptedInput = [[NSCharacterSet illegalCharacterSet] invertedSet];
    }

    // If there are any characters that I do not want in the text field, return NO.
    return ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] <= 1);
}

也请查看UITextFieldDelegate Reference。

Answer 4

我找到了一个简单有效的答案并想分享：

将 EditingChanged 事件的 UITextField 连接到以下 IBAction

-(IBAction) editingChanged:(UITextField*)sender
{    
    if (sender == yourTextField)
    {
        // allow only alphanumeric chars
        NSString* newStr = [sender.text stringByTrimmingCharactersInSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet]];

        if ([newStr length] < [sender.text length])
        {
            sender.text = newStr;
        }
    }
}

Answer 5

Swift 中的 RegEx 方式：

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
     if string.isEmpty {
         return true
     }
     let alphaNumericRegEx = "[a-zA-Z0-9]"
     let predicate = NSPredicate(format:"SELF MATCHES %@", alphaNumericRegEx)
     return predicate.evaluate(with: string)
}

Answer 6

对于斯威夫特： 将事件 EditingChanged 的​​ UITextField 连接到以下 IBAction：

@IBAction func ActionChangeTextPassport(sender:UITextField){
    if sender == txtPassportNum{
        let newStr = sender.text?.stringByTrimmingCharactersInSet(NSCharacterSet.alphanumericCharacterSet().invertedSet)
        if newStr?.characters.count < sender.text?.characters.count{
            sender.text = newStr
        }
    }
}

Answer 7

您必须使用textField delegate 方法，并使用textFieldDidBeginEditing、shouldChangeCharactersInRange 和textFieldDidEndEditing 方法来检查字符。

请参阅this link 获取文档。