Controlling and Scrolling - Learn SpriteBuilder for iOS Game Development - page 86

_playerNode = [_physicsNode getChildByName:@"player"
recursively:YES];
}
Note that in Listing 3-10 it is crucial to get the reference to the _ physicsNode first be-
cause it's being used to search for the player, so it must be assigned by that point. The ver-
sion in Listing 3-10 also doesn't use a recursive search for the _physicsNode and
_backgroundNode because they should always be direct children of the
_levelNode .
Now in the scrollToTarget: method, you need to locate the last line:
_levelNode.positionInPoints = ccpNeg(viewPos);
Replace it with the line in Listing 3-11 in order to reroute the position updates from the
_levelNode to the _physicsNode .
Listing 3-11 . Replace _levelNode with _physicsNode in scrollToTarget
_physicsNode.positionInPoints = ccpNeg(viewPos);
This will decouple the _backgroundNode position so that it can be updated independ-
ently from the _physicsNode position, whereas the _levelNode position will now
remain fixed at 0,0. If you publish, build, and run now, you will notice that the back-
ground layers stay fixed.
To visualize the current layout, look at Figure 3-19 . This is the node hierarchy as returned
by a call to [CCBReader loadAsScene:@"GameScene"] . In brackets are the
CCB files where the content of certain nodes originates from. Note that GameScene, des-
pite its name, is a regular CCNode subclass and not a subclass of CCScene .