NSNotificationCenter *center = [NSNotificationCenter defaultCenter];

    [center addObserver:self selector: @selector(textFiledEditChanged:)

                   name:@"UITextFieldTextDidChangeNotification"

                 object:self.demand_nameField];

#pragma mark - life cycle

- (void)dealloc {

    [[NSNotificationCenter defaultCenter] removeObserver:self];

}

#pragma mark - 监听UITextField文本变化

-(void)textFiledEditChanged:(NSNotification *)obj{

    UITextField *textField = (UITextField *)obj.object;

    NSString *toBeString = textField.text;

    NSArray *currentar = [UITextInputMode activeInputModes];

    UITextInputMode *current = [currentar firstObject];

    if ([current.primaryLanguage isEqualToString:@"zh-Hans"]) { // 简体中文输入，包括简体拼音，健体五笔，简体手写

        UITextRange *selectedRange = [textField markedTextRange];

        //获取高亮部分

        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:];

        // 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 > MAX_LIMIT_NUMSField) {

                [self showHudTipStr:@"超出了限制"];

                textField.text = [toBeString substringToIndex:MAX_LIMIT_NUMSField];

            }

        }

        // 有高亮选择的字符串，则暂不对文字进行统计和限制

        else{

        }

    }

    // 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 > MAX_LIMIT_NUMSField) {

            [self showHudTipStr:@"超出了限制"];

            textField.text = [toBeString substringToIndex:MAX_LIMIT_NUMSField];

        }

    }

}