Build Your Game: Vector Actors and Particles - Beginning iOS6 Games Development - page 156

Figure 7-2. Three saucers and a shield
The shield image is partially transparent and is designed be drawn over a saucer, as can be seen in
the scaled up saucer with the shield drawn over it.
To understand how all the parts and pieces of this example fit together, we will start by looking at the
implementation of the class Example02Controller , starting with the doSetup task, shown in Listing 7-1.
Listing 7-1. Example02Controller.m (doSetup)
-(BOOL)doSetup
{
if ([super doSetup]){
NSMutableArray* classes = [NSMutableArray new];
[classes addObject:[Saucer class]];
[classes addObject:[Bullet class]];
[self setSortedActorClasses:classes];
return YES;
}
return NO;
}
In Listing 7-1, we see the doSetup task of the class Example02Controller . This method simply
indicates that we want to keep actors of type Saucer and Bullet sorted for easy access later on. We
do this by creating an NSMutableArray called classes and adding the class objects for two classes in
which we are interested. The NSMutableArray classes are then passed to setSortedActorClasses: .
This way, when we call actorsOfType: in the future, we will not have to sort through all of the actors
to find them. Next, we want to take a look at the code that describes the action in this example that
is found in the task updateScene of class Example02Controller. See Listing 7-2.