Split UICollectionViewCell (or any view) into two pieces, then send (animation off screen) in opposite directions.

split-cell-animation.m

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
    
    // we are placing it above the collection view, in the VC.view,
    // so convert the rect to that coord. region
    CGRect cellRect = [collectionView convertRect:cell.frame toView:self.view];
    CGRect cellBounds = cell.bounds;
    
    // get an image of the cell
    UIGraphicsBeginImageContextWithOptions(cellRect.size, YES, 1);
    [cell.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *cellImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    // chop the image up
    CGSize portionSize = CGSizeMake(CGRectGetWidth(cellRect), CGRectGetMidY(cellBounds));
    CGImageRef topImageRef = CGImageCreateWithImageInRect(cellImage.CGImage, (CGRect){CGPointZero, portionSize});
    CGImageRef bottomImageRef = CGImageCreateWithImageInRect(cellImage.CGImage, (CGRect){{0, CGRectGetMidY(cellBounds)}, portionSize});
    
    // move portions apart
    CALayer *topLayer = [CALayer layer];
    topLayer.contents = (__bridge id)topImageRef;
    topLayer.frame = (CGRect){cellRect.origin, portionSize};

    CALayer *bottomLayer = [CALayer layer];
    bottomLayer.contents = (__bridge id)bottomImageRef;
    bottomLayer.frame = (CGRect){{CGRectGetMinX(cellRect), CGRectGetMinY(cellRect) + CGRectGetMidY(cellBounds)}, portionSize};
    
    [self.view.layer addSublayer:topLayer];
    [self.view.layer addSublayer:bottomLayer];
    
    cell.hidden = YES;

    // move the layers off screen
    CABasicAnimation *upAnimation = [CABasicAnimation animation];
    // no fromValue needed, current position of layer is used, when not provided
    upAnimation.toValue = @(-CGRectGetHeight(topLayer.bounds));
    upAnimation.removedOnCompletion = NO;
    upAnimation.fillMode = kCAFillModeForwards;
    upAnimation.duration = .9f;
    upAnimation.timingFunction = [CAMediaTimingFunction functionWithName:@"easeIn"];
    [topLayer addAnimation:upAnimation forKey:@"position.y"];
    
    CABasicAnimation *downAnimation = [CABasicAnimation animation];
    downAnimation.toValue = @(CGRectGetHeight(self.view.bounds) + CGRectGetMidY(bottomLayer.bounds));
    downAnimation.removedOnCompletion = NO;
    downAnimation.fillMode = kCAFillModeForwards;
    downAnimation.duration = upAnimation.duration;
    downAnimation.timingFunction = upAnimation.timingFunction;
    [bottomLayer addAnimation:downAnimation forKey:@"position.y"];
}