cocos2d for iPhone

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

1. 

   onedayitwillmake
   Member

   I feel like I must be missing something, but if I have a sprite manager instance and release it from my layer, it crashes cocos2d.
   Here's what I mean, for example

   @interface LittlePhysics : Layer
   {
   
   	AtlasSpriteManager* _spriteManager;
   ....
   }
   
   @property(nonatomic, retain) AtlasSpriteManager* _spriteManager;

   Then in the implimentation:
   

   -(id) init
   {
   	// always call "super" init
   	// Apple recommends to re-assign "self" with the "super" return value
   	if( (self=[super init] ))
   	{
   ...
   // Create the texture for the sprite manager
   		Texture2D* texture = [[TextureMgr sharedTextureMgr] addImage:@"pieces.png"];
   		[texture setAliasTexParameters];
   // Pass in the texture, and create the sprite manager
   		_spriteManager = [AtlasSpriteManager spriteManagerWithTexture:texture];
   		[_spriteManager setBlendFunc:(ccBlendFunc) {GL_ONE, GL_ONE_MINUS_SRC_COLOR }];
   		[self addChild:_spriteManager z:0 tag:0];
   
   ...
       }
   }
   
   - (void) dealloc
   {
   	...
   	[_spriteManager release];
   	[super dealloc];
   }

   If I remove that [_spriteManager release] line, everything is fine. Also if it IS removed, the app runs fine, it doesn't appear to have a memory leak without that line.

   I feel like there's something i'm missing.
   I'm getting ready to maybe try to submit my little free app (http://littlephysics.com) on monday, and I wanna make sure I cross my T's and dot my I's.

   Posted 2 years ago #
2. 

   Codemattic
   Moderator

   Lets see LittlePhysics -init, or show where you set _spriteManager, thats likely the problem. If it gets set in the init then dont forget 'self' - it should be

   self._spriteManager = something;

   Posted 2 years ago #
3. 

   onedayitwillmake
   Member

   I added it to the initial post, so its more clear when coming back.

   I'm not saying, self._spriteManager explicitely however I thought it would be assumed.
   Elsewhere in the code, i reference _spriteManager fine, so it seems that the pointer is valid.

   Posted 2 years ago #
4. 

   onedayitwillmake
   Member

   Whaaaaa, now I'm even more confused. If i say, self.spriteManager in the init, then it works in the dealloc call. So I'm really confused in that case.

   I thought _self was implied? Also why might the pointer work everywhere else in the code?

   Posted 2 years ago #
5. 

   Codemattic
   Moderator

   "I thought _self was implied?"

   Sort of. And yet... no.

   _spriteManager = something;

   is a straight C based call. It doesnt do anything fancy.

   self._spriteManager = something;

   is more complicated. If there is a setter method then it will use that, and only if it cant find one it reverts to the generic C way of setting a variable. And

   @property(nonatomic, retain) AtlasSpriteManager* _spriteManager;

   is just a shorthand way of creating a setter method.

   Its actually not self which is important here - its the dot notation. If I tried to set myVariable from some other class:

   myObjectVariable->myVariable=x; // use C to set myVariable
   myObjectVariable.myVariable=x; // use setter method if available
   [myObjectVariable setMyVariable:x] //same thing as the dot notation

   Posted 2 years ago #
6. 

   onedayitwillmake
   Member

   Thanks codemattic, that definitely made sense and led me to do some reading on the topic which made it make even more sense.
   I wonder why it seemed to still work fine otherwise though.
   --

   Another quesiton I have is, should I go in and do a find and replace on all references in the class?
   For example,
   

   [[_spriteManager getChildByTag:3] setVisible:NO];
   //to
   [[self._spriteManager getChildByTag:3] setVisible:NO];

   I'm not a huge fan of referencing, 'self' or 'this' just looks weird in my eyes maybe it's coming from an actionscript background where 'this' is implied. If that's how it works though in objective-c then that's how it works though, only wondering if it's mainly the setting i should be more worried about calling self on.

   Posted 2 years ago #
7. 

   Codemattic
   Moderator

   nope, the first example uses C and the 2nd example uses a getter method. Doesnt have any effect on retain or release so you dont have to worry about it. There is one tiny hypothetical reason to sometimes use self.myVariable, and that is if in the future you wanted to change the myVariable property into something else you could make it so all the old code still worked. Ive always read about that example, but have never really had to do it, or just find/replace worked just as good for me.

   Posted 2 years ago #

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