Time for action – launching stones

It doesn't take too much time to win our game right now. Just take one step to the left or right and the stone will fall without hitting the hunter. If this is the punishment for shooting birds, then our hunter isn't going to learn anything.

It is time to throw more stones and make them fall at different places to make the hunter run around the level to avoid being hit by stones. Perform the following steps:

1. Open the PhysicsScene.m file, add _timeUntilNextStone, and add the _stones array instance variables, as shown in the following code:

   @implementation PhysicsScene
   {
       //..skipped..
       float _timeUntilNextStone;
       NSMutableArray *_stones;
   }

2. Add the following code to initialize the array and the time counter in the onEnter method, right below the [super onEnter]; line:

   -(void)onEnter
   {
      [super onEnter];
   
       _stones = [NSMutableArray array];
       _timeUntilNextStone = 2.0f;
   
       //..skipped..
   }

3. Then, add the fixedUpdate: method with the...