ios - 如何验证 UITextfield，使其只包含数字，不包含小于 2 的操作系统字符

Question

我想验证我的 UITextfield 字符数少于 2 并且只应输入数字... seen this

Answer 1

试试这个……

#define NUMBERS_ONLY @"1234567890"
#define CHARACTER_LIMIT 2

在这个方法中----

 - (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));
    }