Sparrow Forum

1. 

   christiansson
   Member

   Hi there!

   I am really keen on learning sparrow .. but i have my starting probs .. so i come back to you for my next question ...

   Can I pass events from a child to a parent!? i have a Parent class (derrived from SPSprite) where i add another SPSprite class as child! Her is the code:

   movingObject = [[MovingObject alloc] init];
   [self movingObject];

   Do capsule the Main Class (above) from its objects i want that my "MovingObject" class is firing an Event so my parentClass will know what happend to the "MovingObject" class.

   So I tried to fire the event (in "MovingObject") like this:

   [self.parent addEventListener:@selector(informParentFromDestroyedObject:) atObject:self forType:SP_EVENT_TYPE_TOUCH];

   and in my Parent class i have an EventHandler looking like this:

   -(void)informParentFromDestroyedObject:(SPTouchEvent *)event{
   NSLog(@"informParentFromDestroyedMex");
   }

   Everything compiles fine, no errors. When i execute, the code runs without exceptions BUT the event does not fire or does not reach the parent class.

   thanks for help in advance!!

   chris

   Posted 9 months ago #
2. 

   borrrden
   Moderator

   Is the first code you posted correct? It should be:

   [self addChild:movingObject];

   But maybe you just made a typo here?

   Since the function you want to call is in the parent class, I believe the "atObject" parameter should also be self.parent. Try that.

   Posted 9 months ago #
3. 

   christiansson
   Member

   hi borrrden.. you are right it was a typing error!

   thanks for reply, but the following code does not fix it ... ....

   [self.parent
   addEventListener:@selector(informParentFromDestroyedObject:)
   atObject:self.parent forType:SP_EVENT_TYPE_TOUCH];

   Posted 9 months ago #
4. 

   Chris
   Moderator

   Have you alread tried it?

   [self addEventListener:@selector(informParentFromDestroyedObject:) atObject:self forType:SP_EVENT_TYPE_TOUCH];

   I don't know why, but I remember reading that an event dispatched can be listened anywhere in your code.

   Posted 9 months ago #
5. 

   borrrden
   Moderator

   Oh, silly me, you need to also change the first self.parent to just self. The object being messaged (i.e. the first thing you type in the brackets) is the object that the touch event will be registered with, and "atObject" is the object where the callback function is (if I'm not mistaken...).

   Posted 9 months ago #
6. 

   christiansson
   Member

   hi chris,

   the app crashes when i use your code, and do not implement an EventHandler in the child class .. ... even when the parent class has an EventHandler implemented!!

   any other ideas!? .. hm ...

   Posted 9 months ago #
7. 

   Chris
   Moderator

   I don't have how to test it now, but try borrrden suggestion:

   [movingObject addEventListener:@selector(informParentFromDestroyedObject:) atObject:self.parent forType:SP_EVENT_TYPE_TOUCH];

   as he said, the first thing we type, is the object.

   Posted 9 months ago #
8. 

   christiansson
   Member

   the problem is ... i add the eventlistener in the constructor of the child, so i can not call the object self instead i tried to call [self.parent addEventListener .....

   Visualized

   - SPSprite (Parent)
   *eventlistener (informParentFromDestroyedObject:)
   - movingObject (Child)
   *add eventlistener for parent in constructor ([self.parent addEventListener: ....)

   i really can not fix it .. lol ... thanks for help guys!!

   Posted 9 months ago #
9. 

   scorpion_hub
   Member

   Registering an event for the parent in the childs initialisation won't work - the parent
   is simply not available at this time, it can be accessed first after adding the child to the parent.

   assuming you want to trigger something from the child in the parent
   and the parents creates the child within itself, it should look like this:
   parent code:

   // create and setup moving object code here
   ...
    
   [movingObject addEventListener:@selector(informParentFromDestroyedObject:) atObject:self forType:SP_EVENT_TYPE_TOUCH];

   or from another location which creates the child and the parent:

   // create and setup parent object code here
   ..
    
   // create and setup moving object code here
   ...
    
   [movingObject addEventListener:@selector(informParentFromDestroyedObject:) atObject:parentObject forType:SP_EVENT_TYPE_TOUCH];

   Posted 9 months ago #
10. 

    christiansson
    Member

    Thanks! Clear and straight!!!

    Posted 9 months ago #

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