Escaping from Scrollable areas in tvOS

Question

I understand the concept that the focus engine will decide what can be selected. It also seems that it moves linearly vertically or horizontally and tries to find the next closest neighbor whose view intersects that vertical or horizontal line.

The problem I haven't solved just yet is how to set things up so that panning to switch between focusable subviews does not get prevented if one of them has a scrollable area (like a map).

I have two collection views that take up the width of the screen and sit one on top of the other. I can pan to switch between these just fine. Here is the code that overrides their shared custom UICollectionView class

    override public func canBecomeFocused() -> Bool {
    return true
}

public override func shouldUpdateFocusInContext(context: UIFocusUpdateContext) -> Bool {

    return true
}

public override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {

    super.didUpdateFocusInContext(context, withAnimationCoordinator: coordinator)

}

In a separate view controller, I have a map view and a collection view above it. Both take up the width of the screen. I can pan to switch from the collection view down to the map view, but no matter how slow or fast I try to pan/swipe up, I cannot get the map view to lose its focus.

I did try adding some gesture recognizers and setting the delegate methods to try and make my GR win over the map view's scrolling GRs, but to no avail.

Any one else have similar experience? How do I get back out of the map view without having to add another dialogue or something to switch context back to the collection view?

Thank you in advance.

Answer 1

I'm sure there are a number of ways to solve the problem (like the one suggested in the comment by Eugene for example). In general, you'll probably need to determine when you want the focus to leave the map and trigger a focus update with setNeedsFocusUpdate(), updateFocusIfNeeded(). You would then override preferredFocusView (part of UIFocusEnvironment which is adopted by UIViewController and UIView among other things), to set the focus to whatever you want.

The real trick is to determine when it's appropriate to do this. A map is particularly hard because it's possible that it may scroll for a very long time prior to hitting a boundary (if it ever does). As such, you may need to utilize a button press as suggested by Eugene or perhaps by implementing some of the MKMapViewDelegate methods like mapView(_:regionWillChangeAnimated:) to determine when the map has moved a large distance. The "correct" answer would be determined by your desired behavior, of course.