How to animate UITableViewCell height using auto-layout?

Question

There are lot of similar questions on Stack Overflow about UITableViewCell height animation, but nothing works for new iOS8 auto-layout driven table view. My issue:

Custom cell:

@property (weak, nonatomic) IBOutlet iCarousel *carouselView;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;
@property (weak, nonatomic) IBOutlet UIButton *seeAllButton;
@property (weak, nonatomic) IBOutlet NSLayoutConstraint *carouselHeightConstraint;

Note carouselHeightConstraint. This is height constraint for content view's subview (the only subview).

Height is set to 230.0f for example. On first load it looks like: enter image description here

Then, on See All action I want to expand cell, my code:

- (IBAction)seeAllButtonAction:(id)sender {
  
  BOOL vertical = !self.carouselCell.carouselView.vertical;
  self.carouselCell.carouselView.type = vertical ? iCarouselTypeCylinder : iCarouselTypeLinear;
  self.carouselCell.carouselView.vertical = vertical;

  [UIView transitionWithView:self.carouselCell.carouselView
                    duration:0.2
                     options:0
                  animations:^{
  
    self.carouselCell.carouselHeightConstraint.constant = vertical ? CGRectGetHeight(self.tableView.frame) : 230;
    [self.carouselCell setNeedsUpdateConstraints];
    [self.carouselCell updateConstraintsIfNeeded];
    [self.tableView beginUpdates];
    [self.tableView endUpdates];

                  completion:^(BOOL finished) {
                  }];
}

As you can see, I try to use this good old solution:
Can you animate a height change on a UITableViewCell when selected?

And the result:

enter image description here

My cell shrinks to 44.0f height.

Question:

Why this happens? I expect to see my cell smoothly expanded with magic of auto-layot.

Note:
I dont't want to use -tableView:heightForRowAtIndexPath:. It's auto-layout era, right?

You still need to use tableView:heightForRowAtIndexPath:. That's not an auto-layout job. — Daniyar
@orkenstein I totally agree this should now be done with Auto-Layout. I'm trying to do basically the same thing: setting constraints on the cell's contentView and telling the table view to animate the height. However, I couldn't get it to work so far. Did you find a solution for this problem? — Alex
@Alex, I'v ended up using tableView:heightForRowAtIndexPath:. It looks like the only solution now. Sad but true. Don't forget to update your constraints properly. — orkenstein
@orkenstein I actually did manage to solve my problem after I posted that comment, and I used a pure auto-layout approach: no use of tableView:heightForRowAtIndexPath:. If you're still interested, you can check out my solution here (ExpandableTableViewCell and the sample project). It is still very much work in progress, though (but it works). — Alex

Alex Alex · Accepted Answer · 2015-02-14T15:42:58

The following worked for me:

Preparation:

On viewDidLoad tell the table view to use self-sizing cells:

tableView.rowHeight = UITableViewAutomaticDimension;
tableView.estimatedRowHeight = 44; // Some average height of your cells

Add the constraints as you normally would, but add them to the cell's contentView!

Animate height changes:

Say you change a constraint's constant:

myConstraint.constant = newValue;

...or you add/remove constraints.

To animate this change, proceed as follows:

Tell the contentView to animate the change:

[UIView animateWithDuration: 0.3 animations: ^{ [cell.contentView layoutIfNeeded] }]; // Or self.contentView if you're doing this from your own cell subclass

Then tell the table view to react to the height change with an animation
```
[tableView beginUpdates];
[tableView endUpdates];
```

The duration of 0.3 on the first step is what seems to be the duration UITableView uses for its animations when calling begin/endUpdates.

Bonus - change height without animation and without reloading the entire table:

If you want to do the same thing as above, but without an animation, then do this instead:

[cell.contentView layoutIfNeeded];
[UIView setAnimationsEnabled: FALSE];
[tableView beginUpdates];
[tableView endUpdates];
[UIView setAnimationsEnabled: TRUE];

Summary:

// Height changing code here:
// ...

if (animate) {
    [UIView animateWithDuration: 0.3 animations: ^{ [cell.contentView layoutIfNeeded]; }];
    [tableView beginUpdates];
    [tableView endUpdates];
}
else {
    [cell.contentView layoutIfNeeded];
    [UIView setAnimationsEnabled: FALSE];
    [tableView beginUpdates];
    [tableView endUpdates];
    [UIView setAnimationsEnabled: TRUE];
}

You can check out my implementation of a cell that expands when the user selects it here (pure Swift & pure autolayout - truly the way of the future).

How to animate UITableViewCell height using auto-layout?

Question:

2 Answers