An interface that allows objects to respond to actions triggered by a CALayer change.


protocol CAAction


When queried with an action identifier (a key path, an external action name, or a predefined action identifier) a layer returns the appropriate action object–which must implement the CAAction protocol–and sends it a run(forKey:object:arguments:) message.


Responding to an action

func run(forKey: String, object: Any, arguments: [AnyHashable : Any]?)

Called to trigger the action specified by the identifier.



Conforming Types

See Also

Layer Basics

class CALayer

An object that manages image-based content and allows you to perform animations on that content.

protocol CALayerDelegate

Methods your app can implement to respond to layer-related events.

class CAConstraint

A representation of a single layout constraint between two layers.

protocol CALayoutManager

Methods that allow an object to manage the layout of a layer and its sublayers.

class CAConstraintLayoutManager

An object that provides a constraint-based layout manager.