ios - 放置范围并避免在文本字段中使用特殊字符

Question

我正在使用iOS。我有一个文本字段，其范围应为7位数字，并且还应避免使用特殊字符。我只想输入0-9999999之间的数字。请帮忙

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{    
       if(range.length + range.location > textField.text.length)
       {
          return NO;
       }

        NSUInteger newLength = [textField.text length] + [string length] - range.length;
        return newLength <= 7;

}

Answer 1

用这个

#define acceptableCharacterSet @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:acceptableCharacterSet] invertedSet];

    NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];

    if(![string isEqualToString:filtered])
        return NO;
    NSUInteger newLength = [textField.text length] + [string length] - range.length;
    return (newLength > 7) ? NO : YES;
}