What causes Subviews in iOS to not capture touches?

Question

I'm developing in Xamarin Studio (MonoTouch), but the concept is the same.

I have a UIViewController, and within that UIViewController I've added several subviews that each need to respond to tap events. I attach the UITapGestureRecognizer to my subviews, but they do not fire. Look at "AddExploreButton()" and "AddFollowingButton()".

If I add the gestures to the containing View (MyMenu.View), it does capture the tap gestures, but I need the subviews to handle the events.

What causes my subviews to NOT receive the gestures? (Note I've also set UserInteractionEnabled = true on practically everything).

Secondly, if this is the incorrect coding pattern, how else would I hook up subviews to touch events?

public class MyMenu : UIViewController
{
    private UIImageView _settingsButton;
    private TrendingMenuButton _trendingButton;
    private FollowingMenuButton _followingButton;
    private ExploreMenuButton _exploreButton;
    private NotificationsMenuButton _notificationsButton;

    public MyMenu() { }

    public override void ViewDidLoad() {
        base.ViewDidLoad();

        View.Hidden = true;
        View.UserInteractionEnabled = true;
        View.BackgroundColor = UIColor.FromPatternImage(UIImage.FromBundle("images/menu_bg.png"));
        View.Frame = new RectangleF(0, CityTitleBar.NAV_HEIGHT, 320, 349);

        AddSettingsButton();
        AddTrendingButton();
        AddFollowingButton();
        AddExploreButton();
        AddNotificationsButton();
    }

    private void AddSettingsButton() {
        _settingsButton = new UIImageView(UIImage.FromBundle("images/icon_cogwheel.png"));
        _settingsButton.Frame = new RectangleF(new PointF(269, 12), _settingsButton.Frame.Size);
        View.AddSubview(_settingsButton);
    }

    private void AddTrendingButton() {
        _trendingButton = new TrendingMenuButton(42, 33);
        View.AddSubview(_trendingButton);
    }

    private void AddFollowingButton() {
        _followingButton = new FollowingMenuButton(182, 33);
        _followingButton.AddGestureRecognizer(new UITapGestureRecognizer((g) => {
            MenuHelper.HideMenu();
            NavigationHelper.LoadScreen(new FavoritesScreen());
        }));
        View.AddSubview(_followingButton);
    }

    private void AddExploreButton() {
        _exploreButton = new ExploreMenuButton(42, 187);
        _exploreButton.AddGestureRecognizer(new UITapGestureRecognizer((g) => {
            MenuHelper.HideMenu();
            NavigationHelper.LoadScreen(new ExploreScreen());
        }));
        View.AddSubview(_exploreButton);
    }

    private void AddNotificationsButton() {
        _notificationsButton = new NotificationsMenuButton(182, 187);
        View.AddSubview(_notificationsButton);
    }
}

Answer 1

I found the problem. I was using UIView.SizeToFit() to generate the width and height.

According to this: Having trouble getting UIView sizeToFit to do anything meaningful however, UIView.SizeToFit() does not do anything.

Without the appropriate Frame size, despite being visible, the subviews cannot capture touch events.