Question

I am developing a simple game app.

I am required to have two screens one on left & other on right, just like on scroll view with pagination having 2 screens to toggle between. I am detecting swipes with the help of RootViewController class and successfully swiping left and right screens.

But the problem is I have to have infinitely running rotateBy action on both screens each running this action on single sprite placed on center of screen.

I am using a main scene called SelectWorld & two are it’s sub scenes.
First screen is called factory & other is called stack.
Following is my code:

Select World Screen:

@implementation SelectWorld

+(CCScene*)scene
{
    CCScene* scene = [CCScene node];
    SelectWorld* layer = [SelectWorld node];
    [scene addChild:layer];

    return scene;
}

-(id)init
{
    if((self = [super init]))
    {
        [RootViewController singleton].swipeCallBackHandler = self;
        [[RootViewController singleton] enableSwipeDetection];

        factory = [[ColorfulFactory scene] retain];
        stack = [[CoinsStack scene] retain];

        [self addChild:factory];
        isOnFactory = YES;
    }

    return self;
}

-(void)swipedLeft
{
    if(isOnFactory)
    {
        [self removeAllChildrenWithCleanup:YES];

        isOnFactory = NO;
        CCTransitionScene* transitionalScene = [CCTransitionSlideInR transitionWithDuration:0.3 scene:stack];
        [[CCDirector sharedDirector] replaceScene:transitionalScene];
    }
}

-(void)swipedRight
{
    if(!isOnFactory)
    {
        [self removeAllChildrenWithCleanup:YES];

        isOnFactory = YES;
        CCTransitionScene* transitionalScene = [CCTransitionSlideInL transitionWithDuration:0.3 scene:factory];
        [[CCDirector sharedDirector] replaceScene:transitionalScene];
    }
}

Here’s the code for factory only, same goes for stack-

@implementation ColorfulFactory

+(CCScene*)scene
{
    CCScene* scene = [CCScene node];
    ColorfulFactory* layer = [ColorfulFactory node];
    [scene addChild:layer];

    return scene;
}

-(id)init
{
    if((self = [super init]))
    {
        CGSize size = [CCDirector sharedDirector].winSize;

        CCLabelTTF* info = [CCLabelTTF labelWithString:@"Colorful Factory" fontName:@"Helvetica" fontSize:35.0];
        info.position = ccp(size.width/2, size.height-50);
        [self addChild:info];

        CCSprite* sprite = [CCSprite spriteWithFile:@"Icon.png"];
        sprite.position = ccp(size.width/2, size.height/2);
        [self addChild:sprite];
        sprite.tag = 123;

        CCRotateBy* rotateBy = [CCRotateBy actionWithDuration:60 angle:360.0];
        CCRepeatForever* repeatForever = [CCRepeatForever actionWithAction:rotateBy];
        [sprite runAction:repeatForever];
        repeatForever.tag = 456;
    }

    return self;
}

Now the problem is, in first two swipes actions are running fine, but as soon as I try to swipe more than two or three times, actions got stopped. I haven’t written a single line to stop this in both the classes. I require it there running forever.

Answer 1

Your mistake is that you’re re-using the same scene object for every scene change. You can’t do that in cocos2d, you have to create a new instance of the scene object.

You should never retain a scene object, since there ought to be only one active scene at any one time (with the exception of the duration of a scene transitioning to another scene – but that’s handled by cocos2d internally).

For example:

CCScene* factory = [ColorfulFactory scene];
CCTransitionScene* transitionalScene = [CCTransitionSlideInR transitionWithDuration:0.3 scene:factory];
[[CCDirector sharedDirector] replaceScene:transitionalScene];

If you need both objects in memory, make them layers (or nodes), not scenes. Don’t use replaceScene but instead animate the layers with regular moveTo actions in and out of the screen.