ios - 如何验证 UITextfield 使其只包含数字，没有小于 2 的 os 字符

Question

我想验证我的 UITextfield 的字符数是否小于 2，并且只应输入数字...... 看到这个

Answer 1

试试这个...

#define NUMBERS_ONLY @"1234567890"
#define CHARACTER_LIMIT 2

在这种方法中----

 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string  {
        NSUInteger newLength = [textField.text length] + [string length] - range.length;
        NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:NUMBERS_ONLY] invertedSet];
        NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
        return (([string isEqualToString:filtered])&&(newLength <= CHARACTER_LIMIT));
    }

Answer 2

这行得通！

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{
if ([string isEqualToString:@""]) return YES;
unichar c = [string characterAtIndex:0];
    if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:c])
    {
        int maxVal = 2;
        if (textField.text.length >= maxVal)
            return NO;
        else
            return YES;
    } else {
        return NO;
    }
}

Answer 3

在 iOS 中处理此问题的标准方法是将 a 附加UITextFieldDelegate到您的UITextField, 并实现textField:shouldChangeCharactersInRange:replacementString:方法。在此方法中，您可以验证字符串

使用属性length来实现这一点

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if([textField.text length]<2)
        return YES;
    else
        return NO;
}

Answer 4

试试这样

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if([textField.text length]<2)
        return YES;
    else
        return NO;
}

并将NSNumberkeyboard类型分配给文本字段。

Answer 5

NSCharaterSet用所有字母声明 a 并检查字段文本是否不包含任何字母的另一种方法：

NSCharacterSet *alphabet = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyz"]
if ([[self.label.text lowercaseString] rangeOfCharacterFromSet:alphabet].location != NSNotFound) 
{
     NSLog(@"Found letters!");
}