Create Your Characters: Game Engine, Image Actors, and Behaviors - Beginning iOS6 Games Development - page 128

As you can see, the header for the class GameController extends the class UIViewController . The
UIView named actorsView is an IBOutlet and is the UIView that contains the views for each actor in
the game. We don't want to use the Property view as the root view for the actors because we may
want to have other views associated with a GameController , such as a background image or other
UIViews placed on top of the game. We will take advantage of this setup in a future chapter. For
now, all you need to know is that the UIView actorsView is a sub-view of the Property view and will
contain all of the actor views.
In this listing, you also can see the now familiar CADisplayLink , as well as various collections.
The NSMutableSet actor stores all of the actors in the game. The NSMutableDictionary
actorClassToActorSet is used to keep track of specific types of actors. The two NSMutableSets ,
actorsToBeAdded and actorsToBeRemoved , are used to keep track of actors that are created during a
single step of the game and actors that should be removed after the current step.
The last field declared is the BOOL workComplete . This is used for debugging and will be explained
later in this chapter, when we look at how the CADisplayLink is used. In addition to the fields
declared in Listing 6-1, we see four properties. The first property, stepNumber , keeps track of the
number of steps that have passed since the game started. CGSize gameAreaSize is the size of the
game area in game coordinates. The BOOL isSetup keeps track of whether the GameController has
been set up yet. The last property, sortedActorClasses , is used to tell the GameController which
types of actors it should keep track of.
Setting Up GameController
The use of all of the fields and properties in Listing 6-1 will be made clear as you inspect the
implementation of the class GameController . Let's start with the task doSetup , shown in Listing 6-2.
Listing 6-2. GameController.m (doSetup)
-(BOOL)doSetup
{
if (!isSetup){
gameAreaSize = CGSizeMake(1024, 768);
actors = [NSMutableSet new];
actorsToBeAdded = [NSMutableSet new];
actorsToBeRemoved = [NSMutableSet new];
stepNumber = 0;
workComplete = true;
displayLink = [CADisplayLink displayLinkWithTarget:self selector:
@selector(displayLinkCalled)];
[displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[displayLink setFrameInterval:1];
isSetup = YES;