On Appear is related to the visibility of a layer. Just as the name suggests, On Appear is triggered when a layer appears on the screen. It is useful for:
Tracking analytics
Triggering an action before a layer appears
Executing code when a layer becomes visible to the user (ie. fetching data from a server when a screen is loaded)
The exact moment that On Appear is called depends on the specific layer type that you apply it to, but the Actions parameter completes before the first rendered frame appears.
To add an Action, click on the plus (+) icon in the Actions section and click on “Dismiss” to select an Action. It’s most frequently used with the Custom code integration.
