---
title: kCATransactionCompletionBlock
framework: quartzcore
role: symbol
role_heading: Global Variable
path: quartzcore/kcatransactioncompletionblock
---

# kCATransactionCompletionBlock

## Declaration

```swift
let kCATransactionCompletionBlock: String
```

## Discussion

Discussion A completion block object that is guaranteed to be called (on the main thread) as soon as all animations subsequently added by this transaction group have completed (or have been removed.) If no animations are added before the current transaction group is committed (or the completion block is set to a different value,) the block will be invoked immediately.

## See Also

### Constants

- [kCATransactionAnimationDuration](quartzcore/kcatransactionanimationduration.md)
- [kCATransactionDisableActions](quartzcore/kcatransactiondisableactions.md)
- [kCATransactionAnimationTimingFunction](quartzcore/kcatransactionanimationtimingfunction.md)