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uicollectionviewuicollectionviewlayoutsectionsflowlayout
brigadir
brigadir

Reputation: 6942

UICollectionView - customize item disappearing when section collapses

I collapse & expand sections by toggling numberOfItemsInSection:. When collapsing, items disappear through alpha fade-out. I would like to change this effect to scaling them down.

I think I can implement this with custom UICollectionViewFlowLayout and overloaded layoutAttributesForItemAtIndexPath:. But when section collapses, numberOfItemsInSection: returns 0 - so I can't set destination scale for that items.

What is correct approach?

Upvotes: 1

Views: 1095

Answers (1)

brigadir
brigadir

Reputation: 6942

Have found approach: we need to subclass UICollectionViewFlowLayout and override finalLayoutAttributesForDisappearingItemAtIndexPath:

For example:

- (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDisappearingItemAtIndexPath:(NSIndexPath *)itemIndexPath
{
    UICollectionViewLayoutAttributes *attributes = [super finalLayoutAttributesForDisappearingItemAtIndexPath:itemIndexPath];
    attributes.frame = CGRectInset(attributes.frame, 20, 20);
    return attributes;
}

Upvotes: 1

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