UIView animation in UITableViewCell works only once - ios

Question

Here's a strange fact :
I have a custom UITableViewCell in which I have an animation (an image moves).
It works fine on the creation of the cell.
But once I scroll to hide the cell and then go back on it, the animation has stopped. That, I can understand. But I'm calling my animation method in my viewWillAppear too. And the wired part is that the method is called, I've put a breakpoint in it, nothing is desallocated...
My UITableViewCell is kept strongly (there's a music player in it, the music continues to play). I really don't get it.
Here's my code :
#property (nonatomic, strong) DWPlayerCellVC *playerView;
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"player"];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"player"];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
NSArray *viewsToRemove = [cell.contentView subviews];
for (UIView *v in viewsToRemove) {
[v removeFromSuperview];
}
if(!self.playerView){
self.playerView = [[DWPlayerCellVC alloc] init];
}
[cell.contentView addSubview:self.playerView.view];
self.playerView.model = self.model[indexPath.row];
return cell;
DWPlayerCellVC :
#implementation DWPlayerCellVC
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self zoomIn];
}
- (void)setModel:(id)model
{
_model = model;
// ...
[self zoomIn];
}
- (void)zoomIn
{
UIViewAnimationOptions options =
UIViewAnimationOptionBeginFromCurrentState |
UIViewAnimationOptionCurveEaseInOut |
UIViewAnimationOptionRepeat |
UIViewAnimationOptionAutoreverse;
[UIView
animateWithDuration:10.f
delay:0.f
options:options
animations:^{
CGFloat scale = 1.4f;
self.imageCoverView.transform = CGAffineTransformMakeScale(scale, scale);
} completion:NULL];
}
If you have any ideas...
Thanks a lot !

Answer 1

It looks like the problem is because zoomIn will only ever be called by setModel. This is because UITabelViewCells are not expected to managed displaying UIViewControllers so viewWillAppear: will never be called.
There are two options that I can think of.
The first would be to set up your root view controller to be a containment view controller and add the DWPlayerCellVC as a childViewController. This option does involve some work to get it all running, I suggect reading Creating Custom Container View Controllers to see whets required to get it working.
The second (and the one I would use) would be to create a UITableViewCell subclass that handles running the animation. Then you can just implement the method prepareForReuse to restart the animation. That method is automatically called on a cell when you use dequeueReusableCellWithIdentifier:.

Answer 2

Your UITableViewCell will remember it's state from before. When it's put into the queue (when it scrolls out of view), it doesn't revert back to a pristine state. When you call your ZoomIn method, I think what's happening is that it's zooming in again, but you can't tell because it's already zoomed in.
Try - before you zoom in, ensure that it's zoomed out. So in ViewWillAppear, to a quick "Reset" of the Cell, and then call zoomIn, and see if that fixes the issue.