Question

So I’m trying to implement the alterTime method from the EaseActionsTest example from the Cocos2D example into my game.

I’m trying to implement this idea into my game to create a freeze-time type of powerup for my game. I’ve set up a separate HUDLayer with a CCMenu to change the CCSpeed of the asteroids to 0 to stop moving. I’ve set up a CCLog to make sure my freezeTime method was being called, which it does, but the CCSpeeds of the asteroids remain unaffected. Here is my code for more clarity.

HUDLayer.h

#import "ActionLayer.h"

@interface HUDLayer : CCLayer {
    GameObject *asteroid;
}

-(void)freezeTime:(ccTime)dt;

HUDLayer.mm

-(void)freezeTime:(ccTime)dt
{
    id action = [asteroid getActionByTag:kTagAsteroidAction];
    [action setSpeed:0.0f];
    CCLOG(@"Freeze!");
}

-(void)createPowerUpButtons
{
    CGSize winSize = [CCDirector sharedDirector].winSize;
    CCSprite *freeze = [CCSprite spriteWithSpriteFrameName:@"powerup.png"];
    CCMenuItem *freezeButton = [CCMenuItemImage itemFromNormalSprite:freeze selectedSprite:nil target:self selector:@selector(freezeTime)];

    CCMenu *powerUpMenu = [CCMenu menuWithItems:freezeButton, nil];
    powerUpMenu.position = ccp(winSize.width * 0.5, winSize.height * 0.1);
    [self addChild:powerUpMenu];
}

-(id)init
{
    if( (self = [super init]) )
    {
        [self createPowerUpButtons];
    }
    return self;
}

ActionLayer.h

#import "HUDLayer.h"
#import "GameObject.h"

enum Actions
{
    kTagAsteroidAction = 1
};
@interface ActionLayer : CCLayer
{
    GameObject *asteroid;
}

ActionLayer.mm

-(void)updateAsteroids:(ccTime)dt
{
    // ---------------------------------------------
    //  Code to set random sizes and speeds for the asteroids from the array...
    // ---------------------------------------------

        // Move it offscreen to the left, and when it's done, call removeNode
        id action = [CCSequence actions:
                     [CCMoveBy actionWithDuration:randDuration position:ccp(-winSize.width - asteroid.contentSize.width, 0)],
                     [CCCallFuncN actionWithTarget:self selector:@selector(invisNode:)], nil];
        [action setTag:kTagAsteroidAction];

        [asteroid runAction:[CCSpeed actionWithAction:action speed:1.0f]];

        [self schedule:@selector(freezeTime:) interval:1.0f];
    }
}

-(void)update:(ccTime)dt
{
    [self updateAsteroids:dt];
}

I tried to get as close to as the EaseActionsTest example as I could, but I keep getting this error on startup:

'+[NSInvocation invocationWithMethodSignature:]: method signature argument cannot be nil'

I think it’s because of the -(void)freezeTime:(ccTime)dt, because prior to this, I was originally trying with just -(void)freezeTime; I would receive the CCLog I set in the freezeTime method seeing that it was being called, but the asteroids’ speeds were not affected.

Also, I tried:

-(void)freezeTime
{
    id action = [asteroid getActionByTag:kTagAsteroidAction];
    [action setSpeed:0.1f];
    CCLOG(@"Freeze!");
}

-(id)init
{
    if( (self = [super init]) )
    {
        [self freezeTime];
    }
    return self;
}

I just noticed that the speeds are NOT affected here either.

Any ideas on what I can do to make this work? Any helpful ideas are always appreciated!

Answer 1

Hmm… I think theres a bug on when you are deciding to run the action on your asteroids. Actions are supposed to work over time, and you normally run the action one time, and wait for it to finish. I see you are adding actions to the asteroids EVERY FRAME, which could be the problem. I would change the name of the function as well as how many times its called.

-(void)createAsteroidMovement: (GameObject*) asteroid
{
    // ---------------------------------------------
    //  Code to set random sizes and speeds for the asteroids from the array...
    // ---------------------------------------------

        // Move it offscreen to the left, and when it's done, call removeNode
        id action = [CCSequence actions:
                     [CCMoveBy actionWithDuration:randDuration position:ccp(-winSize.width - asteroid.contentSize.width, 0)],
                 [CCCallFuncN actionWithTarget:self selector:@selector(invisNode:)], nil];
        [action setTag:kTagAsteroidAction];

        [asteroid runAction:[CCSpeed actionWithAction:action speed:1.0f]];

        [self schedule:@selector(freezeTime:) interval:1.0f];
    }
}

-(void)update:(ccTime)dt
{
     if (!_createdAsteroidMovement)
     {
         [self createAsteroidMovement: asteroid];
         _createdAsteroidMovement = true;
     }
}