Animate UICollectionViewCell on Tap - ios6

Question

I would like to start some animation on a UICollectionViewCell when the user taps on a cell. My idea was to select the corresponding cell in didSelectItemAtIndexPath and trigger an animation. However, this doesn't work:
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
// animate the cell user tapped on
ProductCollectionViewCell* cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ProductReuseID" forIndexPath:indexPath];
[UIView animateWithDuration:5.0
delay:0
options:(UIViewAnimationOptionAllowUserInteraction)
animations:^{
NSLog(#"animation start");
[cell.layer setBackgroundColor:[UIColor colorWithRed: 180.0/255.0 green: 238.0/255.0 blue:180.0/255.0 alpha: 1.0].CGColor];
}
completion:^(BOOL finished){
NSLog(#"animation end");
[cell.layer setBackgroundColor:[UIColor whiteColor].CGColor];
}
];
}
Actually, the animation starts and ends at the same time (although animateWithDuration is set to 5). Next attempt was to skip the animation and simply set for instance a different border style:
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
// animate the cell user tapped on
ProductCollectionViewCell* cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ProductReuseID" forIndexPath:indexPath];
[cell.layer setBorderWidth:5.0f];
}
However, this doesn't change anything (probably because I have to redraw the cell manually?).
Do you have any ideas how to animate a UICollectionViewCell when the user tapped on it?
Kind regards,
Christian

Answer 1

It would appear that you are obtaining the wrong Cell. Sending the dequeueReusableCellWithReuseIdentifier:forIndexPath: message does not obtain the cell in use in the view at the indexPath in the second parameter, but dequeues a previously used but reusable cell; if no reusable cell is available, a new one is created. See Reference 1 below.
Replacing:
ProductCollectionViewCell* cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ProductReuseID" forIndexPath:indexPath];
With:
ProductCollectionViewCell* cell = [collectionView cellForItemAtIndexPath:indexPath];
In your code above, should give you the proper cell to work with.
Here is your fist example, rewritten.
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath(NSIndexPath *)indexPath
{
// animate the cell user tapped on
UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
[UIView animateWithDuration:5.0
delay:0
options:(UIViewAnimationOptionAllowUserInteraction)
animations:^{
NSLog(#"animation start");
[cell setBackgroundColor:[UIColor colorWithRed: 180.0/255.0 green: 238.0/255.0 blue:180.0/255.0 alpha: 1.0]];
}
completion:^(BOOL finished){
NSLog(#"animation end");
[cell setBackgroundColor:[UIColor whiteColor]];
}
];
}
References:
http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UICollectionView_class/Reference/Reference.html#//apple_ref/occ/cl/UICollectionView

Answer 2

You can customize the animation while select/tap the UICollectionViewCell with custom animation duration by following the code. So, You don't need to change the background color of it.
With following options - UIViewAnimationOption
UIViewAnimationOptionCurveEaseIn
UIViewAnimationOptionCurveEaseOut
UIViewAnimationOptionAllowUserInteraction
UICollectionViewDelegate - didSelectItemAtIndexPath method
UICollectionViewCell *uviCollectionCell = [collectionView cellForItemAtIndexPath:indexPath];
[UIView animateWithDuration:0.4 delay:0 options:(UIViewAnimationOptionCurveEaseIn) animations:^{
NSLog(#"animation start");
CALayer *layer = uviCollectionCell.layer;
CATransform3D rotationAndPerspectiveTransform = CATransform3DIdentity;
rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, 15.0f * M_PI / 180.0f, 1.0f, 0.0f, 0.0f);
layer.transform = rotationAndPerspectiveTransform;
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.3 delay:0 options:(UIViewAnimationOptionCurveEaseOut) animations:^{
NSLog(#"animation end");
CALayer *layer = uviCollectionCell.layer;
CATransform3D rotationAndPerspectiveTransform = CATransform3DIdentity;
rotationAndPerspectiveTransform.m24 = 0;
rotationAndPerspectiveTransform =CATransform3DRotate(rotationAndPerspectiveTransform, 0.0f * M_PI / 180.0f, 1.0f, 0.0f, 0.0f);
layer.transform = rotationAndPerspectiveTransform;
} completion:nil];
}
];