A mechanism for grouping multiple layer-tree operations into atomic updates to the render tree.
- iOS 2.0+
- macOS 10.5+
- tvOS 9.0+
- Core Animation
CATransaction is the Core Animation mechanism for batching multiple layer-tree operations into atomic updates to the render tree. Every modification to a layer tree must be part of a transaction. Nested transactions are supported.
Core Animation supports two types of transactions: implicit transactions and explicit transactions. Implicit transactions are created automatically when the layer tree is modified by a thread without an active transaction and are committed automatically when the thread's runloop next iterates. Explicit transactions occur when the the application sends the
CATransaction class a
begin message before modifying the layer tree, and a
commit message afterwards.
CATransaction allows you to override default animation properties that are set for animatable properties. You can customize duration, timing function, whether changes to properties trigger animations, and provide a handler that informs you when all animations from the transaction group are completed.
During a transaction you can temporarily acquire a recursive spin lock for managing property atomicity.