Menus & Popovers - Learn SpriteBuilder for iOS Game Development - page 184

precise: it may or may not work, depending on the device in debug configurations, but it
will certainly not work in release configurations.
Tip I recommend adding an NSAssert line directly before the addChild:
line to verify that newMenuLayer is not nil. The popover might be in a differ-
ent folder, there might be a typo in the CCB's name, or the popover CCB file
simply wasn't created or published yet. Those are common and often repeatedly
occuring issues, not just in this example game. It's a good idea to try and catch
those early.
Like the _gameMenuLayer.gameScene before, the _popoverMenuLay-
er.gameScene is assigned to self , to allow methods inside the GameMenuLayer
class to send messages back to the GameScene instance.
When a popover menu is shown, the pause button and other static user interface elements
should be hidden. Setting the _gameMenuLayer.visible to NO effectively hides the
layer and thus the pause button, which in turn makes the button inactive. A button you
can't see is a button you can't touch, so to speak.
Pausing the _levelNode prevents the game from advancing by pausing all of the child
nodes of the levelNode . Pausing a node pauses its Timeline animations, running ac-
tions, and scheduled selectors. Because the _physicsNode is a child of the
_levelNode , the physics world will also be paused.
In order to remove a popover menu, you also need to add the removePopover method
from Listing 6-8 just below the showPopoverNamed: method. It just removes the
node from its parent (the GameScene node) and sets the _popoverMenuLayer ivar
to nil to allow a new popover to appear. Even though the _popoverMenuLayer
should become nil automatically right away, it's a good idea to remind yourself that this
is intentional by explicitly assigning nil .
Listing 6-8 . Removing a popover
-(void) removePopover
{
if (_popoverMenuLayer)
{
[_popoverMenuLayer removeFromParent];