iOS 控制输入框的字数？(textFliedView,textFlied等)

//控制输入框的字数

- (void)textViewDidChange:(UITextView *)textView

{

    NSInteger number = [textView.text length];

    if (number > 300) {

 

        textView.text = [textView.text substringToIndex:300];

        number = 300;

    }

    _evalutionLimitNumberLabel.text=[NSString stringWithFormat:@"%i/300",number];

}