Even when setting a view as modal for accessibility, you may notice that VoiceOver's focus stays in the same place, instead of moving to the presented view. You can post a screen changed notification and pass the view that should get the focus.

Youtube app. VoiceOver focus is on the more options button. The user double taps the screen. The options menu is open, but the focus can remain in the more options button when presenting a modal view in a custom way. For moving the focus to the presented view, you can post a notification to UIAccessibility. The type of the notification is screen changed and the argument, the view you'd like to get the focus, in this case, the draggable view that lets you also close the menu.