[collections] Provide access to the cell factory classes rather than …

…embed size calculations.

Different layouts calculate sizes in different ways so there's no effective
way to define generic layout calculation for collection items.

src/collections/src/NICollectionViewCellFactory.h

@@ -85,65 +85,9 @@ _model.delegate = (id)[NICollectionViewCellFactory class];
  */
 - (void)mapObjectClass:(Class)objectClass toCellClass:(Class)collectionViewCellClass;
 
-/**
- * Returns the size for a view at a given index path.
- *
- * Uses the sizeForObject:atIndexPath:collectionView: selector from the NICollectionViewCell
- * protocol to ask the object at indexPath in the model what its size should be. If a class mapping
- * has been made for the given object in this factory then that class mapping will be used over the
- * result of cellClass from the NICollectionViewCellObject protocol.
- *
- * If the cell returns a size of zero then collectionViewLayout.itemSize will be used.
- *
- * Example implementation:
- *
-@code
-- (CGSize)collectionView:(UICollectionView *)collectionView
-                  layout:(UICollectionViewLayout*)collectionViewLayout
-  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
-  return [self.cellFactory collectionView:collectionView layout:collectionViewLayout sizeForItemAtIndexPath:indexPath model:self.model];
-}
-@endcode
- *
- *      @param collectionView The collection view within which the item exists.
- *      @param layout The layout of the collection view.
- *      @param indexPath The location of the cell in the collection view.
- *      @param model The backing model being used by the collection view.
- *      @returns The size of the cell mapped to the object at indexPath, if it implements
- *               sizeForObject:atIndexPath:tableView:; otherwise, returns
- *               collectionViewLayout.itemSize.
- */
-- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model;
+- (Class)collectionViewCellClassForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model;
 
-/**
- * Returns the size for a view at a given index path.
- *
- * Uses the sizeForObject:atIndexPath:collectionView: selector from the NICollectionViewCell
- * protocol to ask the object at indexPath in the model what its size should be. If a class mapping
- * has been made for the given object in this factory then that class mapping will be used over the
- * result of cellClass from the NICollectionViewCellObject protocol.
- *
- * If the cell returns a size of zero then collectionViewLayout.itemSize will be used.
- *
- * Example implementation:
- *
-@code
-- (CGSize)collectionView:(UICollectionView *)collectionView
-                  layout:(UICollectionViewLayout*)collectionViewLayout
-  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
-  return [NICollectionViewCellFactory collectionView:collectionView layout:collectionViewLayout sizeForItemAtIndexPath:indexPath model:self.model];
-}
-@endcode
- *
- *      @param collectionView The collection view within which the item exists.
- *      @param layout The layout of the collection view.
- *      @param indexPath The location of the cell in the collection view.
- *      @param model The backing model being used by the collection view.
- *      @returns The size of the cell mapped to the object at indexPath, if it implements
- *               sizeForObject:atIndexPath:tableView:; otherwise, returns
- *               collectionViewLayout.itemSize.
- */
-+ (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model;
++ (Class)collectionViewCellClassForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model;
 
 @end
 
@@ -195,34 +139,6 @@ _model.delegate = (id)[NICollectionViewCellFactory class];
  */
 - (BOOL)shouldUpdateCellWithObject:(id)object;
 
-@optional
-
-/**
- * Asks the receiver to calculate its size.
- *
- * The following is an appropiate implementation in your collectionView's delegate:
- *
-@code
-- (CGSize)collectionView:(UICollectionView *)collectionView
-                  layout:(UICollectionViewLayout*)collectionViewLayout
-  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
-  CGFloat size = collectionViewLayout.itemSize;
-  id object = [(NICollectionViewModel *)collectionView.dataSource objectAtIndexPath:indexPath];
-  id class = [object collectionViewCellClass];
-  if ([class respondsToSelector:@selector(sizeForObject:atIndexPath:collectionView:)]) {
-    size = [class sizeForObject:object atIndexPath:indexPath collectionView:collectionView];
-  }
-  return size;
-}
-@endcode
- *
- * You may also use the
- * @link NICollectionViewCellFactory::collectionView:sizeForRowAtIndexPath:model: collectionView:sizeForRowAtIndexPath:model:@endlink
- * methods on NICollectionViewCellFactory to achieve the same result. Using the above example allows you to
- * customize the logic according to your specific needs.
- */
-+ (CGSize)sizeForObject:(id)object atIndexPath:(NSIndexPath *)indexPath collectionView:(UICollectionView *)collectionView;
-
 @end
 
 /**

src/collections/src/NICollectionViewCellFactory.m

@@ -141,41 +141,20 @@ - (void)mapObjectClass:(Class)objectClass toCellClass:(Class)collectionViewCellC
 
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
-- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model {
-  CGSize size = CGSizeZero;
-  if ([collectionViewLayout respondsToSelector:@selector(itemSize)]) {
-    size = [(id)collectionViewLayout itemSize];
-  }
+- (Class)collectionViewCellClassForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model {
   id object = [model objectAtIndexPath:indexPath];
-  Class collectionViewCellClass = [self collectionViewCellClassFromObject:object];
-  if ([collectionViewCellClass respondsToSelector:@selector(sizeForObject:atIndexPath:collectionView:)]) {
-    CGSize cellSize = [collectionViewCellClass sizeForObject:object atIndexPath:indexPath collectionView:collectionView];
-    if (cellSize.width > 0 && cellSize.height > 0) {
-      size = cellSize;
-    }
-  }
-  return size;
+  return [self collectionViewCellClassFromObject:object];
 }
 
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
-+ (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model {
-  CGSize size = CGSizeZero;
-  if ([collectionViewLayout respondsToSelector:@selector(itemSize)]) {
-    size = [(id)collectionViewLayout itemSize];
-  }
++ (Class)collectionViewCellClassForItemAtIndexPath:(NSIndexPath *)indexPath model:(NICollectionViewModel *)model {
   id object = [model objectAtIndexPath:indexPath];
   Class collectionViewCellClass = nil;
   if ([object respondsToSelector:@selector(collectionViewCellClass)]) {
     collectionViewCellClass = [object collectionViewCellClass];
   }
-  if ([collectionViewCellClass respondsToSelector:@selector(sizeForObject:atIndexPath:collectionView:)]) {
-    CGSize cellSize = [collectionViewCellClass sizeForObject:object atIndexPath:indexPath collectionView:collectionView];
-    if (cellSize.width > 0 && cellSize.height > 0) {
-      size = cellSize;
-    }
-  }
-  return size;
+  return collectionViewCellClass;
 }
 
 @end