不错的判断 UITextView 内容不超过20个字符串的方法

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
    
    if ([text isEqualToString:@"
"]){
        [self onSendBarrage:nil];
        return YES;
    }
    NSMutableAttributedString *attrM = [[NSMutableAttributedString alloc]initWithAttributedString:textView.attributedText];
    if (textView == self.textFieldBarrage)
    {
        if (attrM.length > MAX_INPUT_LEN) {
            NSRange range = NSMakeRange(0, MAX_INPUT_LEN);
            textView.attributedText = [attrM attributedSubstringFromRange:range];
        }
        [self fixChatButtonStateWithTextViewLength:attrM.length];
    }
    return YES;
}

以上代码的好处主要在于,先提前计算用户输入的内容,再根据推断出的输入框结果,对输入框的字符进行截取.