UICollectionViewDataSource Protocol Reference
| Conforms to | |
| Framework | /System/Library/Frameworks/UIKit.framework |
| Availability | Available in iOS 6.0 and later. |
| Declared in | UICollectionView.h |
Overview
An object that adopts the UICollectionViewDataSource protocol is responsible for providing the data and views required by a collection view. A data source object represents your app’s data model and vends information to the collection view as needed. It also handles the creation and configuration of cells and supplementary views used by the collection view to display your data.
At a minimum, all data source objects must implement the collectionView:numberOfItemsInSection: and collectionView:cellForItemAtIndexPath: methods. These methods are responsible for returning the number of items in the collection view along with the items themselves. The remaining methods of the protocol are optional and only needed if your collection view organizes items into multiple sections or provides headers and footers for a given section.
When configuring the collection view object, assign your data source to its dataSource property. For more information about how a collection view works with its data source to present content, see UICollectionView Class Reference.
Instance Methods
collectionView:cellForItemAtIndexPath:
Asks the data source for the cell that corresponds to the specified item in the collection view. (required)
Parameters
- collectionView
An object representing the collection view requesting this information.
- indexPath
The index path that specifies the location of the item.
Return Value
A configured cell object.
Discussion
Your implementation of this method is responsible for creating, configuring, and returning the appropriate cell for the given item. You do this by calling the dequeueReusableCellWithReuseIdentifier:forIndexPath: method of the collection view and passing the reuse identifier that corresponds to the cell type you want. That method always returns a valid cell object. Upon receiving the cell, you should set any properties that correspond to the data of the corresponding item, perform any additional needed configuration, and return the cell.
You do not need to set the location of the cell inside the collection view’s bounds. The placement of cells is handled automatically by the layout object in conjunction with the collection view.
Availability
- Available in iOS 6.0 and later.
Declared In
UICollectionView.hcollectionView:numberOfItemsInSection:
Asks the data source for the number of items in the specified section. (required)
Parameters
- collectionView
An object representing the collection view requesting this information.
- section
An index number identifying a section in collectionView. This index value is 0-based.
Return Value
The number of rows in section.
Availability
- Available in iOS 6.0 and later.
Declared In
UICollectionView.hcollectionView:viewForSupplementaryElementOfKind:atIndexPath:
Asks the collection view to provide a supplementary view to display in the collection view.
Parameters
- collectionView
An object representing the collection view requesting this information.
- kind
The kind of supplementary view to provide. The value of this string is defined by the layout object that supports the supplementary view.
- indexPath
The index path that specifies the location of the new supplementary view.
Return Value
A configured supplementary view object.
Discussion
Your implementation of this method is responsible for creating, configuring, and returning the appropriate supplementary view that is being requested. You do this by calling the dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: method of the collection view and passing the information that corresponds to the view you want. That method always returns a valid view object. Upon receiving the view, you should set any properties that correspond to the data you want to display, perform any additional needed configuration, and return the view.
You do not need to set the location of the supplementary view inside the collection view’s bounds. The placement of supplementary views is handled automatically by the layout object in conjunction with the collection view.
Availability
- Available in iOS 6.0 and later.
Declared In
UICollectionView.hnumberOfSectionsInCollectionView:
Asks the data source for the number of sections in the collection view.
Parameters
- collectionView
An object representing the collection view requesting this information.
Return Value
The number of sections in collectionView.
Discussion
If you do not implement this method, the collection view uses a default value of 1.
Availability
- Available in iOS 6.0 and later.
Declared In
UICollectionView.h© 2012 Apple Inc. All Rights Reserved. (Last updated: 2012-09-19)