Custom UICollectionViewCell contentView animation - ios

Question

I change the height of a UICollectionViewCell if a user touches it. To achieve that I use performBatchUpdates: to change the underlying data and use the standard cell animation. This works perfectly and the change gets animated with a standard grow and shrink animation.
Additionally I use reloadSection to update all subviews of the cells in that section. Here is my code:
[collectionView performBatchUpdates:^{
dataHelper.isCellExpanded = !dataHelper.isCellExpanded;
} completion:^(BOOL finished) {
[collectionView reloadSections:[NSIndexSet indexSetWithIndex:indexPath.section]];
}];
I need to achieve a flexible reordering of the subviews for the expanded cell state. So I don't use Auto Layout. I only change the subviews frame and would like to animate the frame change along with the UICollectionViewCell animation.
The Problem is that the subviews inside the contentView of the cells get updated without animation and after the height change animation of the cell is finished. But I would like to animate the cell subviews along with the animation of the height change. How would one implement that?
UPDATE
A custom animation method in my UICollectionViewCell looks like this:
- (void)animate {
[UIView animateWithDuration:1.0
delay:0.0
options:UIViewAnimationOptionCurveLinear
animations:^
{
CGRect labelFrame = self.testLabel.frame;
labelFrame.origin.y += 70;
self.testLabel.frame = labelFrame;
}
completion:nil];
}
I create the testLabel in the initWithFrame: of my UICollectionViewCell subclass like so:
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
CGRect cellFrame = CGRectMake(0, 0, frame.size.width, frame.size.height);
// content
_testLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, frame.size.height - 20, frame.size.width - 20, 20)];
_testLabel.backgroundColor = [UIColor redColor];
_testLabel.textColor = [UIColor blackColor];
_testLabel.text = #"test";
[self.contentView addSubview:_testLabel];
....

Answer 1

You have to implement an animation method inside the collection view cell and you need to that call from the performBatchUpdates method.
[collectionView performBatchUpdates:^{
dataHelper.isCellExpanded = !dataHelper.isCellExpanded;
// Access the cells you want to animate
yourCustomCell *cell = (yourCustomCell *)[collectionView cellForItemAtIndexPath:indexPath];
[cell animate];
} completion:^(BOOL finished) {
[collectionView reloadSections:[NSIndexSet indexSetWithIndex:indexPath.section]];
}];
Inside the cell animate method you can implement all the animations you might want.

Answer 2

I was able to solve this by just adding springs and struts to the contentView and to the testLabel in my UICollectionViewCell subclass in the form of autoresizingMask
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
CGRect cellFrame = CGRectMake(0, 0, frame.size.width, frame.size.height);
self.contentView.autoresizingMask = UIViewAutoresizingFlexibleHeight;
// content
_testLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, frame.size.height - 20, frame.size.width - 20, 20)];
_testLabel.backgroundColor = [UIColor redColor];
_testLabel.textColor = [UIColor blackColor];
_testLabel.text = #"You rock";
_testLabel.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
[self.contentView addSubview:_testLabel];
Side note:
I was playing around with AutoLayout to fix this issue but was never able to get it to work.