UICollectionViewFlowLayoutInvalidationContext Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/UIKit.framework
Availability
Available in iOS 7.0 and later.
Declared in
UICollectionViewFlowLayout.h

Overview

A UICollectionViewFlowLayoutInvalidationContext object specifies properties for determining whether to recompute the size of items or their position in the layout. The flow layout object creates instances of this class when it needs to invalidate its contents in response to changes. You can also create instances when invalidating the flow layout manually.

Tasks

Specifying What to Invalidate

Properties

invalidateFlowLayoutAttributes

A Boolean indicating whether to recompute the layout attributes for items and views in the layout.

@property (nonatomic) BOOL invalidateFlowLayoutAttributes
Discussion

The default value of this property is NO. Set this property to YES if there are changes to the position of items on the screen. For example, the flow layout object sets this property to YES when the collection view’s bounds change in a way that affects the number of items in a column or row.

When this property is set to YES, the flow layout object recomputes the layout attributes for its items and views. If the invalidateFlowLayoutDelegateMetrics property is set to NO it recomputes this information without asking for new size information.

Availability
  • Available in iOS 7.0 and later.
Declared In
UICollectionViewFlowLayout.h

invalidateFlowLayoutDelegateMetrics

A Boolean indicating whether to recompute the size of items and views in the layout.

@property (nonatomic) BOOL invalidateFlowLayoutDelegateMetrics
Discussion

The default value of this property is NO. Set this property to YES if you are invalidating the layout because of changes to the size of any items.

When this property is set to YES, the flow layout object recomputes the size of its items and views, querying the delegate object as needed for that information.

Availability
  • Available in iOS 7.0 and later.
Declared In
UICollectionViewFlowLayout.h