Run animation when returning to an open window

Hello

I am using a window manager for Android and the standard back button for iOS. I'd like to run an animation when the user returns to the page.

I'm wondering if there's a Window event I can subscribe to, or whether I need to execute the animation when the back button is clicked (which I don't think would be optimal since there is a bit of a delay).

I'm new to this paradigm and wanted to see what you recommended.

Thanks,

David