Question

I want to do:

id action = [CCScaleTo actionWithDuration:0.5 scaleX:self.Xposition scaleY:1];
id ease   = [CCEaseInOut actionWithAction:action rate:4];

[someObject[i] runAction:ease];

But I want to be able to hook into each frame of the action to do some stuff… I am wondering if there is any way to accomplish this other than creating an update method on someObject? I am trying to avoid doing that because it’s a CCSprite, and I don’t currently have an object wrapper for it.. It literally is just defined as something like CCSprite *someObject[4] in the header… So I just wondered if there is any way to specify a per-frame callback in the context of runAction?

Answer 1

There is no native way to do this.

If this is what you really want to do rather than using an update method you could create a class similar to how the Ease actions work. Taking another action as a parameter and overriding update to modify its behavior.

For example if you called it CCCallBackAction it would be created as follows:

id action = [CCScaleTo actionWithDuration:0.5 scaleX:self.Xposition scaleY:1];
id ease   = [CCEaseInOut actionWithAction:action rate:4];
id callback = [CCCallBackAction actionWithAction:ease target:self selector:@selector(callback:)];

[someObject[i] runAction:callback];

In CCCallBackAction you would override update

- (void)update:(ccTime)dt
{
     [target performSelector:SEL];
     [other update:dt];
}

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Note to avoid misunderstanding: CCCallBackAction is not a cocos2d class, it is hypothetical in this example