UITableviewCell行高缩小

Question

我有UITableViewCell，有两个标签和一个开关。当切换值更改为状态Off时，我会删除其中一个标签，当更改为On时，会将其添加回视图。我用过自动布局。因此，当我想要添加时，我在删除时添加了丢失的约束。这是我的代码片段

- (void)willUpdateCell:(SampleTableViewCell *)cell{
NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];

if ([cell.messageSwitch isOn]) {
    cell.messageDescription = [UILabel new];
    cell.messageDescription.translatesAutoresizingMaskIntoConstraints = NO;
    cell.messageDescription.text = self.messages[indexPath.row][@"description"];
    cell.messageDescription.numberOfLines = 0;
    cell.messageDescription.lineBreakMode = NSLineBreakByWordWrapping;
    [cell.contentView addSubview:cell.messageDescription];


    cell.left = [NSLayoutConstraint constraintWithItem:cell.messageDescription
                                             attribute:NSLayoutAttributeTrailing
                                             relatedBy:NSLayoutRelationEqual
                                                toItem:cell.messageSwitch
                                             attribute:NSLayoutAttributeTrailing
                                            multiplier:1.0
                                              constant:0];
    cell.bottom = [NSLayoutConstraint constraintWithItem:cell.messageDescription
                                               attribute:NSLayoutAttributeBottom
                                               relatedBy:NSLayoutRelationEqual
                                                  toItem:cell.contentView
                                               attribute:NSLayoutAttributeBottom
                                              multiplier:1.0
                                                constant:15];

    cell.top = [NSLayoutConstraint constraintWithItem:cell.messageDescription
                                            attribute:NSLayoutAttributeTop
                                            relatedBy:NSLayoutRelationEqual
                                               toItem:cell.messageTitle
                                            attribute:NSLayoutAttributeTop
                                           multiplier:1.0
                                             constant:2];


    cell.right = [NSLayoutConstraint constraintWithItem:cell.messageDescription
                                              attribute:NSLayoutAttributeLeading
                                              relatedBy:NSLayoutRelationEqual
                                                 toItem:cell.contentView
                                              attribute:NSLayoutAttributeLeading
                                             multiplier:1.0
                                               constant:15];

    [cell.contentView addConstraints:@[cell.bottom,cell.left,cell.right,cell.top]];

}else{

    [cell.messageDescription removeFromSuperview];
}
 [cell updateFont];
 [cell.contentView updateConstraints];
 [UIView animateWithDuration:0.5 animations:^{
     [cell.contentView setNeedsLayout];
 }];
}

我遇到的问题是当开关状态发生变化时缩小行的高度。删除视图后，间距仍然保留。如果我试图重新加载表，tableview表现得很奇怪。我附上了我的代码here供您参考。请告诉我，当删除子视图时，我可以做些什么来使tableview缩小行高。