接到一个需求：评论输入框控制用户只能输入200个字。于是在

- (BOOL)textView:(UITextView*)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString*)text
{

//添加如下代码
    NSString* toBeString =     [textView.textstringByReplacingCharactersInRange:rangewithString:text];
    if(toBeString.length>self.maxTextInputNum) {
      returnNO;
    }
}

可是这样的话，可以在输入中文的时候无限点击提示，于是各种搜索，找到了以下方法：

适用于textView textField

+ (void)limitTextInputWithNotification: (NSNotification *)noti InMaxLength: (CGFloat)length {
    id textInput;
    if ([noti.object isKindOfClass:[UITextField class]]) {
        textInput = (UITextField *)noti.object;
    } else if ([noti.object isKindOfClass:[UITextView class]]) {
        textInput = (UITextView *)noti.object;
    } else {
        return;
    }
    NSString *toBeString = [textInput text];
//    if ([noti.object isKindOfClass:[UITextField class]]) { //昵称禁止输入表情
//        [textInput setText:[self disable_emoji:[textInput text]]];
//    }
    NSString *lang = [[textInput textInputMode] primaryLanguage];
    if ([lang isEqualToString:@"zh-Hans"])// 简体中文输入
    {
        //获取高亮部分
        UITextRange *selectedRange = [textInput markedTextRange];
        UITextPosition *position = [textInput positionFromPosition:selectedRange.start offset:0];
        
        // 没有高亮选择的字，则对已输入的文字进行字数统计和限制
        if (!position)
        {
            if (toBeString.length > length)
            {
                [textInput setText:[toBeString substringToIndex:length]];
            }
        }
    }
    // 中文输入法以外的直接对其统计限制即可，不考虑其他语种情况
    else
    {
        if (toBeString.length > length)
        {
            NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:length];
            if (rangeIndex.length == 1)
            {
                [textInput setText:[toBeString substringToIndex:length]];
            }
            else
            {
                NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, length)];
                [textInput setText: [toBeString substringWithRange:rangeRange]];
            }
        }
    }

}

使用时候发送通知即可：

 _NC_Add(self, @selector(textViewEditChanged:),UITextViewTextDidChangeNotification, nil);

监听通知：

- (void)textViewEditChanged:(NSNotification *)notif;
{
    [Untitles limitTextInputWithNotification:notif InMaxLength:200];
}