UICollectionViewDataSource Class
Definition
Important
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The data source for a UICollectionView.
[Foundation.Protocol]
[Foundation.Register("UICollectionViewDataSource", false)]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.iOS, 6, 0, ObjCRuntime.PlatformArchitecture.All, null)]
public abstract class UICollectionViewDataSource : Foundation.NSObject, IDisposable, UIKit.IUICollectionViewDataSourcetype UICollectionViewDataSource = class
inherit NSObject
interface IUICollectionViewDataSource
interface INativeObject
interface IDisposable- Inheritance
- Attributes
- Implements
Remarks
As with other parts of iOS, such as UITableView and MKMapView, UICollectionView gets its data from a data source, which is exposed in MonoTouch via the UICollectionViewDataSource class. This class is responsible for providing the content to the UICollectionView including:
- Cells – Returned from GetCell(UICollectionView, NSIndexPath) method.:
- Supplementary Views – Returned from GetViewForSupplementaryElement(UICollectionView, NSString, NSIndexPath) method.:
- Number of sections – Returned from NumberOfSections(UICollectionView) method. Defaults to 1 if not implemented.:
- Number of items per section – Returned from GetItemsCount(UICollectionView, nint) method.:
The UICollectionView maintains a reuse queue, which efficiently reuses UICollectionReusableViews without allocating and de-allocating any more than necessary. The GetCell(UICollectionView, NSIndexPath) and GetViewForSupplementaryElement(UICollectionView, NSString, NSIndexPath) are the functions that mutate the values of UICollectionReusableView component views. Because these methods may be called frequently during scrolling (particularly GetCell(UICollectionView, NSIndexPath)), the application developer should avoid unnecessary calculation in them.
The following code, taken from the "Introduction to Collection Views," shows a simple UICollectionViewDataSource implementation. There are 3 sections and a large animal array representing model data. The number of items per section is 1/3 of the total size of the animals array. The AnimalCell type is a subtype of UICollectionViewCell and is defined as having a UIImageImage property; the GetCell(UICollectionView, NSIndexPath) method sets this property in the reused animalCell from the animals data as appropriate. Similarly, the UICollectionViewDataSource sets the Text property of a Header type defined in the project.
protected const int SectionCount = 3;
public override int NumberOfSections (UICollectionView collectionView)
{
return SectionCount;
}
public override int GetItemsCount (UICollectionView collectionView, int section)
{
return animals.Count / SectionCount;
}
public override UICollectionViewCell GetCell (UICollectionView collectionView, MonoTouch.Foundation.NSIndexPath indexPath)
{
var animalCell = (AnimalCell)collectionView.DequeueReusableCell (animalCellId, indexPath);
var animal = animals [indexPath.Section * (animals.Count / SectionCount) + indexPath.Row];
animalCell.Image = animal.Image;
return animalCell;
}
public override UICollectionReusableView GetViewForSupplementaryElement (UICollectionView collectionView, NSString elementKind, NSIndexPath indexPath)
{
var headerView = (Header)collectionView.DequeueReusableSupplementaryView (elementKind, headerId, indexPath);
headerView.Text = "Supplementary View Section " + indexPath.Section.ToString ();
return headerView;
}
The UICollectionViewSource combines the UICollectionViewDataSource API and the UICollectionViewDelegate API in a single convenience class. Rather than creating two classes to assign to the DataSource and Delegate properties, a single UICollectionViewSource can be created and assigned to the Source property.
Constructors
| UICollectionViewDataSource() |
Default constructor, initializes a new instance of this class. |
| UICollectionViewDataSource(IntPtr) |
A constructor used when creating managed representations of unmanaged objects; Called by the runtime. |
| UICollectionViewDataSource(NSObjectFlag) |
Constructor to call on derived classes to skip initialization and merely allocate the object. |
Properties
| Class | (Inherited from NSObject) |
| ClassHandle |
The handle for this class. (Inherited from NSObject) |
| DebugDescription |
A developer-meaningful description of this object. (Inherited from NSObject) |
| Description |
Description of the object, the Objective-C version of ToString. (Inherited from NSObject) |
| Handle |
Handle (pointer) to the unmanaged object representation. (Inherited from NSObject) |
| IsDirectBinding | (Inherited from NSObject) |
| IsProxy | (Inherited from NSObject) |
| RetainCount |
Returns the current Objective-C retain count for the object. (Inherited from NSObject) |
| Self | (Inherited from NSObject) |
| Superclass | (Inherited from NSObject) |
| SuperHandle |
Handle used to represent the methods in the base class for this NSObject. (Inherited from NSObject) |
| Zone | (Inherited from NSObject) |
Methods
| AddObserver(NSObject, NSString, NSKeyValueObservingOptions, IntPtr) |
Registers an object for being observed externally (using NSString keyPath). Observed changes are dispatched to the observer’s object ObserveValue(NSString, NSObject, NSDictionary, IntPtr) method. (Inherited from NSObject) |
| AddObserver(NSObject, String, NSKeyValueObservingOptions, IntPtr) |
Registers an object for being observed externally (using string keyPath). Observed changes are dispatched to the observer’s object ObserveValue(NSString, NSObject, NSDictionary, IntPtr) method. (Inherited from NSObject) |
| AddObserver(NSString, NSKeyValueObservingOptions, Action<NSObservedChange>) |
Registers an object for being observed externally using an arbitrary method. (Inherited from NSObject) |
| AddObserver(String, NSKeyValueObservingOptions, Action<NSObservedChange>) |
Registers an object for being observed externally using an arbitrary method. (Inherited from NSObject) |
| AwakeFromNib() |
Called after the object has been loaded from the nib file. Overriders must call base.AwakeFromNib(). (Inherited from NSObject) |
| BeginInvokeOnMainThread(Action) | (Inherited from NSObject) |
| BeginInvokeOnMainThread(Selector, NSObject) |
Invokes asynchrously the specified code on the main UI thread. (Inherited from NSObject) |
| Bind(NSString, NSObject, String, NSDictionary) | (Inherited from NSObject) |
| Bind(String, NSObject, String, NSDictionary) |
Obsolete.
(Inherited from NSObject)
|
| BindingInfo(String) |
Obsolete.
(Inherited from NSObject)
|
| BindingOptionDescriptions(String) |
Obsolete.
(Inherited from NSObject)
|
| BindingValueClass(String) |
Obsolete.
(Inherited from NSObject)
|
| CanMoveItem(UICollectionView, NSIndexPath) |
Gets whether the item at can be moved. |
| CommitEditing() | (Inherited from NSObject) |
| CommitEditing(NSObject, Selector, IntPtr) | (Inherited from NSObject) |
| ConformsToProtocol(IntPtr) |
Invoked to determine if this object implements the specified protocol. (Inherited from NSObject) |
| Copy() |
Performs a copy of the underlying Objective-C object. (Inherited from NSObject) |
| DangerousAutorelease() | (Inherited from NSObject) |
| DangerousRelease() | (Inherited from NSObject) |
| DangerousRetain() | (Inherited from NSObject) |
| DidChange(NSKeyValueChange, NSIndexSet, NSString) |
Indicates a change occurred to the indexes for a to-many relationship. (Inherited from NSObject) |
| DidChange(NSString, NSKeyValueSetMutationKind, NSSet) | (Inherited from NSObject) |
| DidChangeValue(String) |
Indicates that a change occurred on the specified key. (Inherited from NSObject) |
| Dispose() |
Releases the resources used by the NSObject object. (Inherited from NSObject) |
| Dispose(Boolean) |
Releases the resources used by the NSObject object. (Inherited from NSObject) |
| DoesNotRecognizeSelector(Selector) |
Indicates that this object does not recognize the specified selector. (Inherited from NSObject) |
| Equals(NSObject) | (Inherited from NSObject) |
| Equals(Object) | (Inherited from NSObject) |
| ExposedBindings() | (Inherited from NSObject) |
| GetBindingInfo(NSString) | (Inherited from NSObject) |
| GetBindingOptionDescriptions(NSString) | (Inherited from NSObject) |
| GetBindingValueClass(NSString) | (Inherited from NSObject) |
| GetCell(UICollectionView, NSIndexPath) |
The cell at the specified indexPath. |
| GetDictionaryOfValuesFromKeys(NSString[]) |
Retrieves the values of the specified keys. (Inherited from NSObject) |
| GetHashCode() |
Generates a hash code for the current instance. (Inherited from NSObject) |
| GetIndexPath(UICollectionView, String, nint) |
Requests the index path for the item in the collection view at the specified index with the specified title. |
| GetIndexTitles(UICollectionView) |
Requests the index titles for the items in the specified collection view. |
| GetItemsCount(UICollectionView, nint) |
The number of items in the specified section. |
| GetMethodForSelector(Selector) | (Inherited from NSObject) |
| GetNativeField(String) |
Obsolete.
(Inherited from NSObject)
|
| GetNativeHash() | (Inherited from NSObject) |
| GetViewForSupplementaryElement(UICollectionView, NSString, NSIndexPath) |
Retrieves the UICollectionReusableView for the specified elementKind at the specified indexPath. |
| Init() | (Inherited from NSObject) |
| InitializeHandle(IntPtr) | (Inherited from NSObject) |
| InitializeHandle(IntPtr, String) | (Inherited from NSObject) |
| Invoke(Action, Double) | (Inherited from NSObject) |
| Invoke(Action, TimeSpan) | (Inherited from NSObject) |
| InvokeOnMainThread(Action) | (Inherited from NSObject) |
| InvokeOnMainThread(Selector, NSObject) |
Invokes synchrously the specified code on the main UI thread. (Inherited from NSObject) |
| IsEqual(NSObject) | (Inherited from NSObject) |
| IsKindOfClass(Class) | (Inherited from NSObject) |
| IsMemberOfClass(Class) | (Inherited from NSObject) |
| MarkDirty() |
Promotes a regular peer object (IsDirectBinding is true) into a toggleref object. (Inherited from NSObject) |
| MoveItem(UICollectionView, NSIndexPath, NSIndexPath) |
Moves the item at to . |
| MutableCopy() |
Creates a mutable copy of the specified NSObject. (Inherited from NSObject) |
| NumberOfSections(UICollectionView) |
The number of sections in the UICollectionView. |
| ObjectDidEndEditing(NSObject) | (Inherited from NSObject) |
| ObserveValue(NSString, NSObject, NSDictionary, IntPtr) |
Indicates that the value at the specified keyPath relative to this object has changed. (Inherited from NSObject) |
| PerformSelector(Selector) | (Inherited from NSObject) |
| PerformSelector(Selector, NSObject) | (Inherited from NSObject) |
| PerformSelector(Selector, NSObject, Double) |
Invokes the selector on the current instance and if the |
| PerformSelector(Selector, NSObject, Double, NSString[]) | (Inherited from NSObject) |
| PerformSelector(Selector, NSObject, NSObject) | (Inherited from NSObject) |
| PerformSelector(Selector, NSThread, NSObject, Boolean) | (Inherited from NSObject) |
| PerformSelector(Selector, NSThread, NSObject, Boolean, NSString[]) | (Inherited from NSObject) |
| PrepareForInterfaceBuilder() | (Inherited from NSObject) |
| RemoveObserver(NSObject, NSString) |
Stops the specified observer from receiving further notifications of changed values for the specified keyPath. (Inherited from NSObject) |
| RemoveObserver(NSObject, NSString, IntPtr) |
Stops the specified observer from receiving further notifications of changed values for the specified keyPath and context. (Inherited from NSObject) |
| RemoveObserver(NSObject, String) |
Stops the specified observer from receiving further notifications of changed values for the specified keyPath. (Inherited from NSObject) |
| RemoveObserver(NSObject, String, IntPtr) |
Stops the specified observer from receiving further notifications of changed values for the specified keyPath and context. (Inherited from NSObject) |
| RespondsToSelector(Selector) |
Whether this object recognizes the specified selector. (Inherited from NSObject) |
| SetNativeField(String, NSObject) |
Obsolete.
(Inherited from NSObject)
|
| SetNilValueForKey(NSString) |
Sets the value of the specified key to null. (Inherited from NSObject) |
| SetValueForKey(NSObject, NSString) |
Sets the value of the property specified by the key to the specified value. (Inherited from NSObject) |
| SetValueForKeyPath(IntPtr, NSString) |
A constructor used when creating managed representations of unmanaged objects; Called by the runtime. (Inherited from NSObject) |
| SetValueForKeyPath(NSObject, NSString) |
Sets the value of a property that can be reached using a keypath. (Inherited from NSObject) |
| SetValueForUndefinedKey(NSObject, NSString) |
Indicates an attempt to write a value to an undefined key. If not overridden, raises an NSUndefinedKeyException. (Inherited from NSObject) |
| SetValuesForKeysWithDictionary(NSDictionary) |
Sets the values of this NSObject to those in the specified dictionary. (Inherited from NSObject) |
| ToString() |
Returns a string representation of the value of the current instance. (Inherited from NSObject) |
| Unbind(NSString) | (Inherited from NSObject) |
| Unbind(String) |
Obsolete.
(Inherited from NSObject)
|
| ValueForKey(NSString) |
Returns the value of the property associated with the specified key. (Inherited from NSObject) |
| ValueForKeyPath(NSString) |
Returns the value of a property that can be reached using a keypath. (Inherited from NSObject) |
| ValueForUndefinedKey(NSString) |
Indicates an attempt to read a value of an undefined key. If not overridden, raises an NSUndefinedKeyException. (Inherited from NSObject) |
| WillChange(NSKeyValueChange, NSIndexSet, NSString) |
Indicates that the values of the specified indices in the specified key are about to change. (Inherited from NSObject) |
| WillChange(NSString, NSKeyValueSetMutationKind, NSSet) | (Inherited from NSObject) |
| WillChangeValue(String) |
Indicates that the value of the specified key is about to change. (Inherited from NSObject) |