CLASS

RenderContext

public class RenderContext<WorkflowType: Workflow>: RenderContextType

RenderContext is the composition point for the workflow tree.

During a render pass, a workflow may want to defer to a child workflow to render some portion of its content. For example, a workflow that renders to a split-screen view model might delegate to child A for the left side, and child B for the right side view models. Nesting allows for a fractal tree that is constructed out of many small parts.

If a parent wants to delegate to a child workflow, it must first create an instance of that workflow. This can be thought of as the model of the child workflow. It does not contain any active state, it simply contains the data necessary to create or update a workflow node.

The parent then calls render(workflow:outputMap:) with two values: - The child workflow. - A closure that transforms the child’s output events into the parent’s Event type so that the parent can respond to events generated by the child.

If the parent had previously rendered a child of the same type, the existing child workflow node is updated.

If the parent had not rendered a child of the same type in the previous render pass, a new child workflow node is generated.

The infrastructure then performs a render pass on the child to obtain its Rendering value, which is then returned to the caller.

Methods

makeSink(of:)

public func makeSink<Action>(of actionType: Action.Type) -> Sink<Action> where Action: WorkflowAction, Action.WorkflowType == WorkflowType

Creates a Sink that can be used to send Actions.

Sinks are the primary mechanism for feeding State-changing events into the Workflow runtime. Upon receipt of an action, the associated Workflow (node) in the tree will have its State potentially transformed, and then any subsequent Output will be propagated to its parent node until the root of the Workflow tree is reached. At this point the tree will be re-rendered to reflect any State changes that occurred.

• Parameter actionType: The type of Action this Sink may process
• Returns: A Sink capable of relaying Action instances to the Workflow runtime

Parameters

Name	Description
actionType	The type of Action this Sink may process

runSideEffect(key:action:)

public func runSideEffect(key: AnyHashable, action: (Lifetime) -> Void)

Execute a side-effect action.

Note that it is a programmer error to run two side-effects with the same key during the same render pass.

action will be executed the first time a side-effect is run with a given key. runSideEffect calls with a given key on subsequent renders are ignored.

If after a render pass, a side-effect with a key that was previously used is not used, it’s lifetime ends and the Lifetime object’s onEnded closure will be called.

• Parameters:
• key: represents the block of work that needs to be executed.
• action: a block of work that will be executed.

Parameters

Name	Description
key	represents the block of work that needs to be executed.
action	a block of work that will be executed.