iphone - UITextField 限制字符的数量和类型

Question

我有两个文本字段，我想限制字符的数量和类型。我已使用以下代码位分别执行每个功能，但找不到在同一功能内执行这两项操作的方法。

限制字符类型:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // Only characters in the NSCharacterSet you choose will insertable.
    NSCharacterSet *invalidCharSet = [[NSCharacterSet characterSetWithCharactersInString:@"abcdefgABCDEFG"] invertedSet];
    NSString *filtered = [[string componentsSeparatedByCharactersInSet:invalidCharSet] componentsJoinedByString:@""];
    return [string isEqualToString:filtered];
}

并限制字符数:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 if (textField.text.length >= 10 && range.length == 0)
 return NO;
return YES;
}

Answer 1

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField.text.length >= 10 && range.length == 0)
       return NO;
    // Only characters in the NSCharacterSet you choose will insertable.
    NSCharacterSet *invalidCharSet = [[NSCharacterSet characterSetWithCharactersInString:@"abcdefgABCDEFG"] invertedSet];
    NSString *filtered = [[string componentsSeparatedByCharactersInSet:invalidCharSet] componentsJoinedByString:@""];
    return [string isEqualToString:filtered];
}

---

已编辑

如果你想为第三个文本字段添加不同的条件，那么你可以这样做。
为第三个文本字段创建引用 thirdField

然后用这个

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField == thirdField) {
        //your contion e.g
        if (textField.text.length < 7) {
            return YES;
        } else {
            return NO;
        }        
    }
    else {
        if (textField.text.length >= 10 && range.length == 0)
            return NO;
        // Only characters in the NSCharacterSet you choose will insertable.
        NSCharacterSet *invalidCharSet = [[NSCharacterSet characterSetWithCharactersInString:@"abcdefgABCDEFG"] invertedSet];
        NSString *filtered = [[string componentsSeparatedByCharactersInSet:invalidCharSet] componentsJoinedByString:@""];
        return [string isEqualToString:filtered];
    }
}