如何限制textField中输入字符的个数

一般，当我们需要限制textfield的输入字符限制时，调用- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string方法来实现，比如：
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (self.remarkname == textField) //判断是否时我们想要限定的那个输入框
{
NSString * toBeString = [self.remarkname.text stringByReplacingCharactersInRange:range withString:string];
if (range.location >= 8)
{
return NO;
}
return YES;
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (range.location >= 2)
return NO; // return NO to not change text
return YES;
}
//限制长度为2