Custom actions are also great for actions that are executed with a gesture that is overridden by VoiceOver. Think of the unread, flag and archive hidden options that you can make visible by swiping left/right on a message row in the Mail app.

The mail app lets you swipe to the right in a message row to unveil an Unread option. You can swipe left to unveil the More, Flag and archive options. With VoiceOver, those same gestures would bring you to the next and previous elements in the screen instead. You can put those kind of options in the custom actions of the row. That way, when the row is focused, you can swipe up/down to cycle through the different actions, and double tap to execute them.