Level changing problem « cocos2d for iPhone

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Level changing problem

(10 posts) (2 voices)

Started 1 year ago by mrcointreau
Latest reply from Dragyn

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mrcointreau
Member

Hello everybody, I'd need a little help with the my game's level changing strategy.
I have the following GameScene class:

@interface GameScene : CCScene {
    HUDLayer *hudLayer;
    InputLayer *inputLayer;
    Level *levelLayer;
    PoorStudent *poorStudent;
}

@property (nonatomic, readwrite, assign) Level *levelLayer;

+ (GameScene *)sceneWithLevel:(int)levelNumber;
+ (GameScene *)sharedScene;

- (id)initWithLevelNumber:(int)levelNumber

@end

@implementation GameScene

@synthesize levelLayer;

static GameScene *instanceOfGameScene;

+ (id)sceneWithLevel:(int)levelNumber {
    GameScene *scene = [[[GameScene alloc] initWithLevelNumber:levelNumber] autorelease];

    return scene;
}

+ (GameScene *)sharedScene {
    return instanceOfGameScene;
}

- (id)initWithLevelNumber:(int)levelNumber {
    if ((self = [super init])) {
        if (instanceOfGameScene == nil) {

            instanceOfGameScene = self;

            // Load all of the game's artwork
            CCSpriteFrameCache* frameCache = [CCSpriteFrameCache sharedSpriteFrameCache];
            [frameCache addSpriteFramesWithFile:@"game-art.plist"];

            poorStudent = [PoorStudent poorStudent];

            hudLayer = [HUDLayer HUDLayerWithHealth:poorStudent.health andScore:0];
            [self addChild:hudLayer z:1];

            inputLayer = [InputLayer node];
            [self addChild:inputLayer z:2];

            levelLayer = [Level levelWithLevelNumber:levelNumber];
            [levelLayer addChild:poorStudent z:0];
            [self addChild:levelLayer z:0];

            CGSize screenSize = [[CCDirector sharedDirector] winSize];
            [poorStudent setPosition:ccp(poorStudent.contentSize.width, screenSize.height / 2)];
            [levelLayer runAction:[CCFollow actionWithTarget:poorStudent worldBoundary:CGRectMake(0, 0, levelLayer.contentSize.width, levelLayer.contentSize.height)]];

            [self scheduleUpdate];
        }
    }
    return instanceOfGameScene;
};

which is a singleton class.
I use the sceneWithLevel method for the first call to the GameScene instance.
I'm trying to change the level by using the following method:

- (void)loadLevel:(int)levelNumber {
    [self removeChild:levelLayer cleanup:YES];
    levelLayer = [Level levelWithLevelNumber:levelNumber];
    [levelLayer addChild:poorStudent];
}

but when I call it I've got the following error:
Assertion failure in -[Level addChild:z:tag:]
NSAssert( child.parent == nil, @"child already added. It can't be added again");

Could somebody help me with this, please?

Posted 1 year ago #

Dragyn
Moderator

From that error, my best guess is that something else in your code is keeping the levelLayer alive. Check for anything else that might be retaining a reference to the levelLayer, because the "cleanup" will only take care of children of the CCLayer, not outside references. If this is the case, it's somewhere other than the code snippet you posted.

I'm curious why your main game is apparently in a Singleton. For what it's worth, I've found this type of uber-singleton to be more problematic because it's not as "clean" if you want to reset your level. I generally take the approach of using a Singleton to hold persisted values (and any load/save methods), but let the actual main game scene be a separate, non-singleton. This lets you persist values in the Singleton, but if you have a need to completely reset the game scene (restart or going to a new level), you can do it with a simple replaceScene, and replace it with a new instance of itself. Just my 2 cents worth.

Posted 1 year ago #
mrcointreau
Member

First of all, thanks for your reply.
I use a singleton for my GameScene because i only need one GameScene at time and I don't want more than one to be allocated. Is it wrong?

Posted 1 year ago #
Dragyn
Moderator

No, not wrong. There are many ways to accomplish your goals, and if your way works for you (and you can keep everything straightforward when you change levels), then go for it.

To debug your layer problem, I was just thinking it might be an interesting test to set up a test method that you can trigger in your scene that only performs the "removeChild" portion of the loadLevel method. Run this through Instruments, and see if that layer actually goes away. If not, then start walking the code to see what you've retained or alloc'd, and make sure it all gets put away when you're done. The most common things I've seen are related to arrays or touch delegates. If you're explicitly registered for touch handling, make sure you get rid of it in the onExit (or before).

Good luck!

Posted 1 year ago #
mrcointreau
Member
Maybe the problem is that in my GameScene class I have set the HUDLayer, the LevelLayer, the InputLayer and my PlayerSprite as instance variable and retained them. I did it because I have many methods where I access to them and I want to call getChild every time to retrieve a node.
So my GameScene interface is:
```
@interface GameScene : CCScene {
    HUDLayer *hudLayer;
    InputLayer *inputLayer;
    Level *levelLayer;
    PoorStudent *poorStudent;
}
```
and in my GameScene init method I retain all of them and add them as child.

Could this be the problem? I'm getting mad!
Posted 1 year ago #
Dragyn
Moderator

I think I see what might be the problem. I completely missed that you had declared the levelLayer as a property. You should use self.levelLayer, so it uses the getter/setter for the property. When you bypass the setter, it doesn't call a release before it assigns the new value. You should change this everywhere you are giving a new value to levelLayer (both in the initWithLevelNumber and the loadLevel method).

Let me know if that helps.

Posted 1 year ago #
mrcointreau
Member

Does levelLayer become a property even without the @property declaration and the @syntesize commmand???

Posted 1 year ago #
Dragyn
Moderator

No, it doesn't. However, from the code you posted in the first post, both of those declarations are in your code.

Posted 1 year ago #
mrcointreau
Member

You're right, my back Dragyn, now I got it, thank you very much!
It was more than a month that I didn't touch the game so I made some mess with the memory management, thanks :)

Posted 1 year ago #
Dragyn
Moderator

Glad to help.

Good luck!

Posted 1 year ago #

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