弹出 collectionview 单元格并缩放 - uicollectionviewcell 动画

Question

Im trying to create a cool animation with my collection view selection. Basically I have a collection view of photo cells displayed. What I want to happen is have the cell pop out of its location, scale and move to the center of the screen where the user will be prompted to confirm the selection.

Here is my code so far, but currently the animation takes the cells original frame location, so if I scroll it doesnt take into account that the frame position is no longer the same.

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{

PhotoCell *cell = (PhotoCell *)[collectionView cellForItemAtIndexPath:indexPath];
collectionView.allowsSelection = NO;
[self createAnimationWithCell:cell];

}

- (void)createAnimationWithCell:(PhotoCell *)cell {

UIImageView *selectedImage = [[UIImageView alloc] initWithFrame:cell.bounds];
selectedImage.center = cell.center;
selectedImage.image = cell.imageView.image;
[self.view addSubview:selectedImage];

[UIView animateWithDuration:2.5 animations:^{
    selectedImage.center = self.view.center;
} completion:^(BOOL finished) {
    [selectedImage removeFromSuperview];
    self.collectionView.allowsSelection = YES;
}];
}

Answer 1

I solved it myself:

For those who are experiencing the same problem, we have to take into account how much the collection view has scrolled (offset) and use that information. I created a variable called collectionViewOffset and gave it an initial value of 0.0

then used:

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    // getting the scroll offset
    collectionViewOffset = scrollView.contentOffset.y;
    NSLog(@"offset: %f", collectionViewOffset);
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{

      PhotoCell *cell = (PhotoCell *)[collectionView cellForItemAtIndexPath:indexPath];
      //collectionView.allowsSelection = NO;
      //collectionView.scrollEnabled = NO;

     [cell.superview bringSubviewToFront:cell];
     [UIView animateWithDuration:2.0 delay:0 usingSpringWithDamping:0.7 initialSpringVelocity:.2 options:UIViewAnimationOptionCurveLinear animations:^{
     cell.center = CGPointMake(self.view.vWidth/2, self.bannerView.vBottomEdge + collectionViewOffset + 40);
     } completion:^(BOOL finished) {

     }];
}