UICollectionViewLayout Class

Reference

Definition

Namespace:: UIKit

Assembly:: Xamarin.iOS.dll

Important

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Base class for specifying the layout of a UICollectionView.

[Foundation.Register("UICollectionViewLayout", true)]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.iOS, 6, 0, ObjCRuntime.PlatformArchitecture.All, null)]
public class UICollectionViewLayout : Foundation.NSObject, Foundation.INSCoding, IDisposable

type UICollectionViewLayout = class
    inherit NSObject
    interface INSCoding
    interface INativeObject
    interface IDisposable

Inheritance: Object

NSObject
UICollectionViewLayout

Derived: UIKit.UICollectionViewFlowLayout

UIKit.UICollectionViewTransitionLayout

Attributes: RegisterAttribute IntroducedAttribute

Implements: INSCoding INativeObject IDisposable

Remarks

Collection Views allow content to be displayed using arbitrary layouts. Grid-like layouts can use the UICollectionViewFlowLayout or application developers can subtype UICollectionViewLayout to create their own flexible pattern.

The layout of the UICollectionViewCells in a UICollectionView is controlled by a UICollectionViewLayout, which can be passed in to the C:UIKit.UICollectionView(UICollectionViewLayout) constructor or can changed with SetCollectionViewLayout.

Application developers can create fully custom layouts by subclassing either UICollectionViewFlowLayout or UICollectionViewLayout.

The key methods to override are:

Method	Description
PrepareLayout()	Used for performing initial geometric calculations that will be used throughout the layout process.
CollectionViewContentSize	Returns the size of the area used to display content.
LayoutAttributesForElementsInRect(CGRect)	Returns the layout attributes for all the cells and views within the specified rectangle.
LayoutAttributesForItem(NSIndexPath)	The layout attributes of a specific cell
ShouldInvalidateLayoutForBoundsChange(CGRect)	Returns `true` if the new bounds require an update of the layout.

The following code, taken from the "Introduction to Collection Views" class, creates a circular layout, as shown in the following image:

public override UICollectionViewLayoutAttributes LayoutAttributesForItem (NSIndexPath path)
{
  UICollectionViewLayoutAttributes attributes = UICollectionViewLayoutAttributes.CreateForCell (path);
  attributes.Size = new SizeF (ItemSize, ItemSize);

  attributes.Center = new PointF (center.X + radius * (float)Math.Cos (2 * path.Row * Math.PI / cellCount),
    center.Y + radius * (float)Math.Sin (2 * path.Row * Math.PI / cellCount));
  return attributes;
}

Constructors

UICollectionViewLayout()	Default constructor, initializes a new instance of this class.
UICollectionViewLayout(IntPtr)	A constructor used when creating managed representations of unmanaged objects; Called by the runtime.
UICollectionViewLayout(NSCoder)	A constructor that initializes the object from the data stored in the unarchiver object.
UICollectionViewLayout(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.
CollectionView	The UICollectionView which this UICollectionViewLayout is laying out.
CollectionViewContentSize	The SizeF of this UICollectionViewLayout's content.
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)
DevelopmentLayoutDirection	Gets the language direction that was used during development.
FlipsHorizontallyInOppositeLayoutDirection	Gets a Boolean that tells whether the coordinate system horizontally reverses for reversed layout directions.
Handle	Handle (pointer) to the unmanaged object representation. (Inherited from NSObject)
IsDirectBinding	(Inherited from NSObject)
IsProxy	(Inherited from NSObject)
LayoutAttributesClass	The UICollectionViewLayoutAttributes used for layout attributes for this UICollectionViewLayout.
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)
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)
EncodeTo(NSCoder)	Encodes the state of the object on the provided encoder
Equals(NSObject)	(Inherited from NSObject)
Equals(Object)	(Inherited from NSObject)
ExposedBindings()	(Inherited from NSObject)
FinalizeAnimatedBoundsChange()	When overridden, performs custom cleanup after animated changes to the bounds or after items have been inserted or deleted.
FinalizeCollectionViewUpdates()	When overridden, allows additional animations or clean up during an update.
FinalizeLayoutTransition()	Called prior to transition animations, informs the layout object to perform any steps necessary before the animations.
FinalLayoutAttributesForDisappearingDecorationElement(NSString, NSIndexPath)	The final layout information for a decoration element that is about to be removed from this UICollectionViewLayout.
FinalLayoutAttributesForDisappearingItem(NSIndexPath)	The final layout information for an item that is about to be removed from the UICollectionView.
FinalLayoutAttributesForDisappearingSupplementaryElement(NSString, NSIndexPath)	The final layout information for a supplementary view that is about to be removed from the collection view.
GetBindingInfo(NSString)	(Inherited from NSObject)
GetBindingOptionDescriptions(NSString)	(Inherited from NSObject)
GetBindingValueClass(NSString)	(Inherited from NSObject)
GetDictionaryOfValuesFromKeys(NSString[])	Retrieves the values of the specified keys. (Inherited from NSObject)
GetHashCode()	Generates a hash code for the current instance. (Inherited from NSObject)
GetIndexPathsToDeleteForDecorationViewOfKind(NSString)	An array of NSIndexPaths indicating the decoration views to remove.
GetIndexPathsToDeleteForSupplementaryView(NSString)	An array of NSIndexPaths indicating the supplementary views to remove.
GetIndexPathsToInsertForDecorationView(NSString)	An array of NSIndexPaths indicating the decoration views to add.
GetIndexPathsToInsertForSupplementaryView(NSString)	An array of index paths indicating the supplementary views to add.
GetInvalidationContext(UICollectionViewLayoutAttributes, UICollectionViewLayoutAttributes)	Gets the invalidated areas for a change from `originalAttributes` to `preferredAttributes`.
GetInvalidationContextForBoundsChange(CGRect)	Returns a UICollectionViewLayoutInvalidationContext that specifies the portions of the layout that change in response to a change in bounds.
GetInvalidationContextForEndingInteractiveMovementOfItems(NSIndexPath[], NSIndexPath[], Boolean)	Returns a validation context for the moved items.
GetInvalidationContextForInteractivelyMovingItems(NSIndexPath[], CGPoint, NSIndexPath[], CGPoint)	Gets a UICollectionViewLayoutInvalidationContext that identifies the items being moved.
GetLayoutAttributesForInteractivelyMovingItem(NSIndexPath, CGPoint)	Returns the layout attributes for items that the user is moving.
GetMethodForSelector(Selector)	(Inherited from NSObject)
GetNativeField(String)	Obsolete. (Inherited from NSObject)
GetNativeHash()	(Inherited from NSObject)
GetTargetIndexPathForInteractivelyMovingItem(NSIndexPath, CGPoint)	Returns the target index path for items that the user is moving.
Init()	(Inherited from NSObject)
InitializeHandle(IntPtr, String)	(Inherited from NSObject)
InitializeHandle(IntPtr)	(Inherited from NSObject)
InitialLayoutAttributesForAppearingDecorationElement(NSString, NSIndexPath)	Information on the starting layout of a decoration view that is being inserted into the UICollectionView.
InitialLayoutAttributesForAppearingItem(NSIndexPath)	Information on the starting layout of an item that is being inserted into the UICollectionView.
InitialLayoutAttributesForAppearingSupplementaryElement(NSString, NSIndexPath)	Information on the starting layout of a supplementary view that is being inserted into the UICollectionView.
InvalidateLayout()	Invalidates the current layout and initiates an update.
InvalidateLayout(UICollectionViewLayoutInvalidationContext)	Forces recomputation and application of the collection view.
InvalidationContextClass()	The custom UICollectionViewLayoutInvalidationContext used for this UICollectionViewLayout.
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)
LayoutAttributesForDecorationView(NSString, NSIndexPath)	The UICollectionViewLayoutAttributes for the specified decoration view.
LayoutAttributesForElementsInRect(CGRect)	The UICollectionViewLayoutAttributes for all the cells and views in the specified RectangleF.
LayoutAttributesForItem(NSIndexPath)	The UICollectionViewLayoutAttributes for the specified NSIndexPath.
LayoutAttributesForSupplementaryView(NSString, NSIndexPath)	The UICollectionViewLayoutAttributes for the specified supplementary view.
LayoutAttributesForSupplementaryView(UICollectionElementKindSection, NSIndexPath)	The attributes for the supplementary view at the specified indexPath.
MarkDirty()	Promotes a regular peer object (IsDirectBinding is true) into a toggleref object. (Inherited from NSObject)
MutableCopy()	Creates a mutable copy of the specified NSObject. (Inherited from NSObject)
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, NSObject, Double, NSString[])	(Inherited from NSObject)
PerformSelector(Selector, NSObject, Double)	Invokes the selector on the current instance and if the `obj` is not null, it passes this as its single parameter. (Inherited from NSObject)
PerformSelector(Selector, NSObject, NSObject)	(Inherited from NSObject)
PerformSelector(Selector, NSObject)	(Inherited from NSObject)
PerformSelector(Selector, NSThread, NSObject, Boolean, NSString[])	(Inherited from NSObject)
PerformSelector(Selector, NSThread, NSObject, Boolean)	(Inherited from NSObject)
PerformSelector(Selector)	(Inherited from NSObject)
PrepareForAnimatedBoundsChange(CGRect)	Called prior to animated changes to the bounds or before insertion or deletion of items.
PrepareForCollectionViewUpdates(UICollectionViewUpdateItem[])	Notifies the layout object that the contents of the UICollectionView are about to change.
PrepareForInterfaceBuilder()	(Inherited from NSObject)
PrepareForTransitionFromLayout(UICollectionViewLayout)	Notifies the layout object that it will shortly be installed as the layout for the UICollectionView.
PrepareForTransitionToLayout(UICollectionViewLayout)	Tells the layout object that it will shortly be removed as the layout for the UICollectionView.
PrepareLayout()	Tells the layout object to update the layout.
RegisterClassForDecorationView(Type, NSString)	Registers the class identified by kind as a decoration view.
RegisterNibForDecorationView(UINib, NSString)	Registers the UINib for use as a template for decoration views.
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, NSString)	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)
RemoveObserver(NSObject, String)	Stops the specified observer from receiving further notifications of changed values for the specified keyPath. (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)
ShouldInvalidateLayout(UICollectionViewLayoutAttributes, UICollectionViewLayoutAttributes)	Returns true if the collection view needs to invalidate for a change from `preferredAttributes` to `originalAttributes`.
ShouldInvalidateLayoutForBoundsChange(CGRect)	Whether the new bounds requires a layout update.
TargetContentOffset(CGPoint, CGPoint)	The PointF at which to stop scrolling.
TargetContentOffsetForProposedContentOffset(CGPoint)	The content offset to use after an animated layout change.
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)

Extension Methods

GetDebugDescription(INSObjectProtocol)
GetAccessibilityCustomRotors(NSObject)	Gets the array of UIAccessibilityCustomRotor objects appropriate for `this` object.
SetAccessibilityCustomRotors(NSObject, UIAccessibilityCustomRotor[])	Sets the array of UIAccessibilityCustomRotor objects appropriate for `this` object.

Applies to

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