How to expand collectionview cell on didselect to show more info?

问题

I want to animate my collectionview cell so that when I touch it, a mapview slides out from underneath it and basically expands into the space, by pushing the cell underneath it down a little bit. I tried using this: UICollectionView: Animate cell size change on selection, but was unable to get it to work properly.

Here what I tried.

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

    [((FeedCell *)[collectionView cellForItemAtIndexPath:indexPath]) setIsSelected:YES];

     [collectionView.collectionViewLayout invalidateLayout];
    __weak FeedCell *cell = (FeedCell *)[self.photoCollectionView cellForItemAtIndexPath:indexPath]; // Avoid retain cycles
    void (^animateChangeWidth)() = ^()
    {
        CGRect frame = cell.frame;
        frame.size = CGSizeMake(frame.size.width, 420);
        cell.frame = frame;
    };

    // Animate

    [UIView transitionWithView:[collectionView cellForItemAtIndexPath:indexPath] duration:0.5f options: UIViewAnimationOptionCurveLinear animations:animateChangeWidth completion:nil];

}



- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

    if(((FeedCell *)[self.photoCollectionView cellForItemAtIndexPath:indexPath]).isSelected == YES){
        return CGSizeMake(320, 420);
    }
     return CGSizeMake(320, 320);

}

I have a custom CollectionView cell and it has a property for isSelected. I'm not sure what I should do for the xib of the cell (whether to put the map view in there, have the CGSize be the selected size or deselected size, etc.) Any help would really be appreciated!

回答1:

I am trying to do the same thing as you and found your question in my search. It appears that you have a pretty good solution (at least in my inexperienced opinion). What isn't working for you? I got it to do what I wanted by copying your code almost verbatim. I changed a few things, but didn't test the code before making the changes. Here is what I have that works for me in my didSelectItemAtIndexPath method:

__weak MyCell *cell = (MyCell*)[collectionView cellForItemAtIndexPath:indexPath];
[cell setSelected:YES];

[collectionView.collectionViewLayout invalidateLayout];
void (^animateChangeWidth)() = ^()
{
    CGRect frame = cell.frame;
    frame.size = CGSizeMake(frame.size.width, 340.0f);
    cell.frame = frame;
};

// Animate

[UIView transitionWithView:cell duration:0.5f options: UIViewAnimationOptionCurveEaseInOut animations:animateChangeWidth completion:nil];

I also have overridden collectionView:layout:sizeForItemAtIndexPath so I assume that is working for you as well.

Sorry I can't be more specific. It would help if you said what about it wasn't working.

来源：https://stackoverflow.com/questions/19058169/how-to-expand-collectionview-cell-on-didselect-to-show-more-info