Fix edge case with target content offset (#117)

MagazineLayout/Public/MagazineLayout.swift

@@ -277,16 +277,18 @@ public final class MagazineLayout: UICollectionViewLayout {
  override public func prepare(forAnimatedBoundsChange oldBounds: CGRect) {
  super.prepare(forAnimatedBoundsChange: oldBounds)
 
- targetContentOffsetAnchor = targetContentOffsetAnchor(
- bounds: oldBounds,
- contentHeight: preInvalidationContentSize?.height ?? currentCollectionView.contentSize.height,
- // There doesn't seem to be a reliable way to get the correct content insets here. We can try
- // track them in invalidateLayout or prepare, but then there are edge cases where we need to
- // track multiple past inset values. It's a huge mess, and I don't think it's worth solving.
- // The downside is that if your insets change on rotation, you won't always land in the exact
- // correct spot if you're in the middle of the content. Being at the top or bottom works fine.
- topInset: 0,
- bottomInset: 0)
+ if currentCollectionView.bounds.size != oldBounds.size {
+ targetContentOffsetAnchor = targetContentOffsetAnchor(
+ bounds: oldBounds,
+ contentHeight: preInvalidationContentSize?.height ?? currentCollectionView.contentSize.height,
+ // There doesn't seem to be a reliable way to get the correct content insets here. We can try
+ // track them in invalidateLayout or prepare, but then there are edge cases where we need to
+ // track multiple past inset values. It's a huge mess, and I don't think it's worth solving.
+ // The downside is that if your insets change on rotation, you won't always land in the exact
+ // correct spot if you're in the middle of the content. Being at the top or bottom works fine.
+ topInset: 0,
+ bottomInset: 0)
+ }
  }
 
  override public func finalizeAnimatedBoundsChange() {