cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   SDKTutor
   Member

   Hi! I am working on an awesome new app and I have a question. In my app, I have a CCSprite subclass file (I need to create an instance of this a lot). This file will control everything about itself, eg. shooting or something in that nature depending on realtime game play elements... So I have some timers and statements that will check whether the conditions are right for something to occur, and when they are, I do this:
   

   // creates a new bullet sprite
   CCSprite *bullet = [CCSprite spriteWithFile:@"bullet.png"];
   // assigns its position to the sprites position
   bullet.position = self.position;
   // get the current instance of the gamescene class
   GameScene *scene = [GameScene node];
   // add the bullet to the gamescene class
   [scene addChild:bullet];

   The code seems right, except it isn't adding it to the GameScene layer. When I do GameScene *scene = [GameScene node]; Does that create a new instance of the GameScene class? That's the only explanation for this behavior. If it does, how do I go about accessing the current instance of the GameScene class, so I can do interaction with it? I know this is possible, I'm just not sure how. I have tried many many ways, but they all have the same result. How would you go about doing this? Please help if you can. Thanks in advance!

   Posted 2 years ago #
2. 

   Steve Oldmeadow
   Administrator

   Hold down the command key and double click on "node" in your source code. Then you'll see:

   +(id) node
   {
   	return [[[self alloc] init] autorelease];
   }

   that shows you what node does. You also seem to be getting confused between scenes and layers.

   Posted 2 years ago #
3. 

   alien_ken
   Member

   If your code is in the layer you want to add it to, just do
   

   [self addChild:bullet];

   Otherwise, you need to get a reference to the layer you want to add it to. If your code is in the scene and you want to add the bullet to a particular layer, assuming you've already added the layer to the scene earlier, you would use [self getChildByTag] to get a reference to the layer, like:
   

   [[self getChildByTag:1] addChild:bullet];

   Or if the code is in one layer of a scene, and you want to add the bullet to a different scene, you could do:
   

   [[[self parent] getChildByTag:1] addChild:bullet];

   where "1" is the tag of the target layer.

   Posted 2 years ago #
4. 

   leocck
   Member

   Yes, calling node function you'll create a new GameScene's instance, and that's a bad thing.

   You can make it works by creating your bullet instances directly inside GameScene's init method.

   After that, if you need to call a GameScene method from your bullet instances you only need to get their parent reference ('cos you added they on your GameScene already).

   Posted 2 years ago #
5. 

   SDKTutor
   Member

   Ok. I see now. If I create a sprite in one file, but I want to add it to the layer in another file, what code would I do to do that?

   Posted 2 years ago #
6. 

   SDKTutor
   Member

   I'll have a visual representation of it tomorrow, in case you don't understand.

   Posted 2 years ago #
7. 

   Codemattic
   Moderator

   as Steve said [GameScene node] creates a *new* GameScene. That new GameScene isnt added to anything, so anything added to it isnt part of the game's animation.

   "Ok. I see now. If I create a sprite in one file, but I want to add it to the layer in another file, what code would I do to do that? "

   Do a search for globals and singletons and how to pass variables to objects. If you have a main layer that many other objects will be adding new sprites to - maybe make it a global variable.

   Posted 2 years ago #

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