---
title: transitionProgress
framework: appkit
role: symbol
role_heading: Instance Property
path: appkit/nscollectionviewtransitionlayout/transitionprogress
---

# transitionProgress

The completion percentage of the transition.

## Declaration

```swift
var transitionProgress: CGFloat { get set }
```

## Discussion

Discussion During the transition, set the value of this property periodically and call the invalidateLayout() method to force the collection view to update item positions. For example, when driving a transition using a gesture recognizer, you can set this property from the handler method of your gesture recognizer.

## See Also

### Updating the Transition Information

- [updateValue(_:forAnimatedKey:)](appkit/nscollectionviewtransitionlayout/updatevalue(_:foranimatedkey:).md)
- [value(forAnimatedKey:)](appkit/nscollectionviewtransitionlayout/value(foranimatedkey:).md)
- [NSCollectionViewTransitionLayout.AnimatedKey](appkit/nscollectionviewtransitionlayout/animatedkey.md)