IGListCollectionContext
@protocol IGListCollectionContext <NSObject>
The collection context provides limited access to the collection-related information that section controllers need for operations like sizing, dequeing cells, insterting, deleting, reloading, etc.
-
The size of the collection view. You may use this for sizing cells.
Declaration
Objective-C
@property (readonly, nonatomic) CGSize containerSize;
Swift
var containerSize: Int32 { get }
-
Returns the index of the specified cell in the collection relative to the section controller.
Declaration
Objective-C
- (NSInteger)indexForCell:(nonnull UICollectionViewCell *)cell sectionController:(nonnull IGListSectionController<IGListSectionType> *) sectionController;
Swift
func index(forCell cell: Any!, sectionController: Any!) -> Any!
Parameters
cell
An existing cell in the collection.
sectionController
The section controller requesting this information.
Return Value
The index of the cell or
NSNotFound
if it does not exist in the collection. -
Returns the cell in the collection at the specified index for the section controller.
Warning
This method may return
nil
if the cell is offscreen.Declaration
Objective-C
- (nullable __kindof UICollectionViewCell *) cellForItemAtIndex:(NSInteger)index sectionController: (nonnull IGListSectionController<IGListSectionType> *)sectionController;
Swift
func cellForItem(atIndex index: Any!, sectionController: Any!) -> Any!
Parameters
index
The index of the desired cell.
sectionController
The section controller requesting this information.
Return Value
The collection view cell, or
nil
if not found. -
Returns the visible cells for the given section controller.
Declaration
Objective-C
- (nonnull NSArray<UICollectionViewCell *> *)visibleCellsForSectionController: (nonnull IGListSectionController<IGListSectionType> *)sectionController;
Swift
func visibleCells(forSectionController sectionController: Any!) -> Any!
Parameters
sectionController
The section controller requesting this information.
Return Value
An array of visible cells, or an empty array if none are found.
-
Deselects a cell in the collection.
Declaration
Objective-C
- (void)deselectItemAtIndex:(NSInteger)index sectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController animated:(BOOL)animated;
Swift
func deselectItem(atIndex index: Any!, sectionController: Any!, animated: Any!)
Parameters
index
The index of the item to deselect.
sectionController
The section controller requesting this information.
animated
Pass
YES
to animate the change,NO
otherwise. -
Returns the section index of an section controller.
Declaration
Objective-C
- (NSInteger)sectionForSectionController: (nonnull IGListSectionController<IGListSectionType> *)sectionController;
Swift
func section(forSectionController sectionController: Any!) -> Any!
Parameters
sectionController
An section controller object.
Return Value
The section index of the controller if found, otherwise
NSNotFound
. -
Dequeues a cell from the collection view reuse pool.
Note
This method uses a string representation of the cell class as the identifier.
Declaration
Objective-C
- (nonnull __kindof UICollectionViewCell *) dequeueReusableCellOfClass:(nonnull Class)cellClass forSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndex:(NSInteger)index;
Swift
func dequeueReusableCell(of cellClass: AnyClass!, forSectionController sectionController: Any!, atIndex index: Any!) -> Any!
Parameters
cellClass
The class of the cell you want to dequeue.
sectionController
The section controller requesting this information.
index
The index of the cell.
Return Value
A cell dequeued from the reuse pool or a newly created one.
-
Dequeues a cell from the collection view reuse pool.
Note
This method uses a string representation of the cell class as the identifier.
Declaration
Objective-C
- (nonnull __kindof UICollectionViewCell *) dequeueReusableCellWithNibName:(nonnull NSString *)nibName bundle:(nullable NSBundle *)bundle forSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndex:(NSInteger)index;
Swift
func dequeueReusableCell(withNibName nibName: Any!, bundle: Any!, forSectionController sectionController: Any!, atIndex index: Any!) -> Any!
Parameters
nibName
The name of the nib file.
bundle
The bundle in which to search for the nib file. If
nil
, this method searches the main bundle.sectionController
The section controller requesting this information.
index
The index of the cell.
Return Value
A cell dequeued from the reuse pool or a newly created one.
-
Dequeues a storyboard prototype cell from the collection view reuse pool.
Declaration
Objective-C
- (nonnull __kindof UICollectionViewCell *) dequeueReusableCellFromStoryboardWithIdentifier:(nonnull NSString *)identifier forSectionController: (nonnull IGListSectionController< IGListSectionType> *)sectionController atIndex:(NSInteger)index;
Swift
func dequeueReusableCellFromStoryboard(withIdentifier identifier: Any!, forSectionController sectionController: Any!, atIndex index: Any!) -> Any!
Parameters
identifier
The identifier of the cell prototype in storyboard.
sectionController
The section controller requesting this information.
index
The index of the cell.
Return Value
A cell dequeued from the reuse pool or a newly created one.
-
Dequeues a supplementary view from the collection view reuse pool.
Note
This method uses a string representation of the view class as the identifier.
Declaration
Objective-C
- (nonnull __kindof UICollectionReusableView *) dequeueReusableSupplementaryViewOfKind:(nonnull NSString *)elementKind forSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController class:(nonnull Class)viewClass atIndex:(NSInteger)index;
Swift
func dequeueReusableSupplementaryView(ofKind elementKind: Any!, forSectionController sectionController: Any!, class viewClass: AnyClass!, atIndex index: Any!) -> Any!
Parameters
elementKind
The kind of supplementary veiw.
sectionController
The section controller requesting this information.
viewClass
The class of the supplementary view.
index
The index of the supplementary vew.
Return Value
A supplementary view dequeued from the reuse pool or a newly created one.
-
Dequeues a supplementary view from the collection view reuse pool.
Declaration
Objective-C
- (nonnull __kindof UICollectionReusableView *) dequeueReusableSupplementaryViewFromStoryboardOfKind: (nonnull NSString *)elementKind withIdentifier: (nonnull NSString *)identifier forSectionController: (nonnull IGListSectionController< IGListSectionType> *)sectionController atIndex:(NSInteger)index;
Swift
func dequeueReusableSupplementaryView(fromStoryboardOfKind elementKind: Any!, withIdentifier identifier: Any!, forSectionController sectionController: Any!, atIndex index: Any!) -> Any!
Parameters
elementKind
The kind of supplementary veiw.
identifier
The identifier of the supplementary view in storyboard.
sectionController
The section controller requesting this information.
index
The index of the supplementary vew.
Return Value
A supplementary view dequeued from the reuse pool or a newly created one.
-
Dequeues a supplementary view from the collection view reuse pool.
Note
This method uses a string representation of the view class as the identifier.
Declaration
Objective-C
- (nonnull __kindof UICollectionReusableView *) dequeueReusableSupplementaryViewOfKind:(nonnull NSString *)elementKind forSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController nibName:(nonnull NSString *)nibName bundle:(nullable NSBundle *)bundle atIndex:(NSInteger)index;
Swift
func dequeueReusableSupplementaryView(ofKind elementKind: Any!, forSectionController sectionController: Any!, nibName: Any!, bundle: Any!, atIndex index: Any!) -> Any!
Parameters
elementKind
The kind of supplementary veiw.
sectionController
The section controller requesting this information.
nibName
The name of the nib file.
bundle
The bundle in which to search for the nib file. If
nil
, this method searches the main bundle.index
The index of the supplementary vew.
Return Value
A supplementary view dequeued from the reuse pool or a newly created one.
-
Reloads cells in the section controller.
Declaration
Objective-C
- (void)reloadInSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndexes:(nonnull NSIndexSet *)indexes;
Swift
func reload(inSectionController sectionController: Any!, atIndexes indexes: Any!)
Parameters
sectionController
The section controller who’s cells need reloading.
indexes
The indexes of items that need reloading.
-
Inserts cells in the list.
Declaration
Objective-C
- (void)insertInSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndexes:(nonnull NSIndexSet *)indexes;
Swift
func insert(inSectionController sectionController: Any!, atIndexes indexes: Any!)
Parameters
sectionController
The section controller who’s cells need inserting.
indexes
The indexes of items that need inserting.
-
Deletes cells in the list.
Declaration
Objective-C
- (void)deleteInSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndexes:(nonnull NSIndexSet *)indexes;
Swift
func delete(inSectionController sectionController: Any!, atIndexes indexes: Any!)
Parameters
sectionController
The section controller who’s cells need deleted.
indexes
The indexes of items that need deleting.
-
Reloads the entire section controller.
Declaration
Objective-C
- (void)reloadSectionController: (nonnull IGListSectionController<IGListSectionType> *)sectionController;
Swift
func reloadSectionController(_ sectionController: Any!)
Parameters
sectionController
The section controller who’s cells need reloading.
-
Batches and performs many cell-level updates in a single transaction.
Note
Use this method to batch cell updates (inserts, deletes, reloads) into a single transaction. This lets you make many changes to your data store and perform all the transitions at once.
For example, inside your section controllers, you may want to delete and insert into the data source that backs your section controller. For example:
[self.collectionContext performBatchItemUpdates:^{ // perform data source changes inside the update block [self.items addObject:newItem]; [self.items removeObjectAtIndex:0]; NSIndexSet *inserts = [NSIndexSet indexSetWithIndex:[self.items count] - 1]; [self.collectionContext insertInSectionController:self atIndexes:inserts]; NSIndexSet *deletes = [NSIndexSet indexSetWithIndex:0]; [self.collectionContext deleteInSectionController:self atIndexes:deletes]; } completion:nil];
Warning
You must perform data modifications inside the update block. Updates will not be performed synchronously, so you should make sure that your data source changes only when necessary.Declaration
Objective-C
- (void)performBatchAnimated:(BOOL)animated updates:(nonnull void (^)())updates completion:(nullable void (^)(BOOL))completion;
Swift
func performBatchAnimated(_ animated: Any!, updates: (() -> Void)!, completion: ((Int32) -> Void)? = nil)
Parameters
animated
A flag indicating if the transition should be animated.
updates
A block containing all of the cell updates.
completion
An optional completion block to execute when the updates are finished.
-
Scrolls to the specified section controller in the list.
Declaration
Objective-C
- (void)scrollToSectionController: (nonnull IGListSectionController<IGListSectionType> *) sectionController atIndex:(NSInteger)index scrollPosition:(UICollectionViewScrollPosition)scrollPosition animated:(BOOL)animated;
Swift
func scroll(toSectionController sectionController: Any!, atIndex index: Any!, scrollPosition: Any!, animated: Any!)
Parameters
sectionController
The section controller.
index
The index of the item in the section controller to which to scroll.
scrollPosition
An option that specifies where the item should be positioned when scrolling finishes.
animated
A flag indicating if the scrolling should be animated.