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# NSCollectionViewTransitionLayout

An object that implements custom behaviors when changing from one layout to another in a collection view.

```
class NSCollectionViewTransitionLayout
```

## Overview

Transition layout objects are commonly used to implement interactive transitions between layouts, where the transition itself is driven by a gesture recognizer.

> Note:
> In macOS 10.11, collection views do not provide built-in support for driving layout transitions.

## Topics

### Initializing the Transition Layout Object

[`init(currentLayout:nextLayout:)`](/documentation/AppKit/NSCollectionViewTransitionLayout/init(currentLayout:nextLayout:))

Initializes and returns the transition layout object.

### Updating the Transition Information

[`transitionProgress`](/documentation/AppKit/NSCollectionViewTransitionLayout/transitionProgress)

The completion percentage of the transition.

[`updateValue(_:forAnimatedKey:)`](/documentation/AppKit/NSCollectionViewTransitionLayout/updateValue(_:forAnimatedKey:))

Sets the value of a key whose value you use during the animation.

[`value(forAnimatedKey:)`](/documentation/AppKit/NSCollectionViewTransitionLayout/value(forAnimatedKey:))

Returns the most recently set value for the specified key.

[`NSCollectionViewTransitionLayout.AnimatedKey`](/documentation/AppKit/NSCollectionViewTransitionLayout/AnimatedKey)

### Accessing the Layout Objects

[`currentLayout`](/documentation/AppKit/NSCollectionViewTransitionLayout/currentLayout)

The collection view’s current layout object.

[`nextLayout`](/documentation/AppKit/NSCollectionViewTransitionLayout/nextLayout)

The collection view’s new layout object.


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