Instance Method

targetContentOffsetForProposedContentOffset:

Returns the offset value to use after an animated layout update or change.

Declaration

- (NSPoint)targetContentOffsetForProposedContentOffset:(NSPoint)proposedContentOffset;

Parameters

proposedContentOffset

The proposed point (in the collection view’s coordinate space) for the lower-left corner of the visible content. The collection view calculates this value as the most likely value to use at the end of animations.

Return Value

The offset value that you want to use for the content.

Discussion

During layout updates, or when transitioning between layouts, the collection view calls this method to give you the opportunity to tweak the position of the collection view’s content at the end of animations. The default implementation of this method returns the value in the proposedContentOffset parameter. Subclasses can override it and return an offset value that positions content in a way that is more optimal for the custom layout.

See Also

Providing Layout Information

layoutAttributesClass

Returns the class to use for layout attribute objects

- prepareLayout

Prepares the layout object to begin laying out content.

collectionViewContentSize

The width and height of the collection view’s contents.

- layoutAttributesForElementsInRect:

Returns the layout attribute objects for all items and views in the specified rectangle.

- layoutAttributesForItemAtIndexPath:

Returns the layout attributes for the item at the specified index path.

- layoutAttributesForSupplementaryViewOfKind:atIndexPath:

Returns the layout attributes of the supplementary view at the specified location in your layout.

- layoutAttributesForDecorationViewOfKind:atIndexPath:

Returns the layout attributes of the decoration view at the specified location in your layout.

- layoutAttributesForDropTargetAtPoint:

Returns layout attributes for the drop target at the specified point.

- layoutAttributesForInterItemGapBeforeIndexPath:

Returns layout attributes for the inter-item gap at the specified location in your layout.

- targetContentOffsetForProposedContentOffset:withScrollingVelocity:

Returns the offset value to use for the collection view’s content at the end of scrolling.