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.