Playing with cocos2d and this seems to come up in some instances of message passing. I have to admit, I'm not well versed in Objective-C yet as I'm reading through the book as I write some code.
For people familiar with cocos2d, you have a CCLayer class. In my case, I have a GameLayer which has some children layers, like so:
@interface GameLayer : CCLayer {
CCSprite *_background;
CCPanZoomController *_controller;
CCLayer *_truckLayer;
}
I then have a special initWithLayers method to add my child layers within this layer:
-(id)initWithLayers:(TruckLayer *)truck
{
if( (self=[super init])) {
self.truckLayer = truck;
.....
}
Now if I ever send a message to self.truckLayer I get the following warning in Xcode:
'CCLayer' may not respond to 'getNextAvailableSpot'
An example might be doing something like so:
CGPoint nextSpot = [self.truckLayer getNextAvailbleSpot];
All this code compiles and runs successfully, so I'm curious as to what I am missing here? I don't want my code literred with these if I'm doing something wrong here.
It's because your declare *_truckLayer as CCLayer, but on your init you assign (TruckLayer *)truck to your CCLayer* _truckLayer. So CCLayer doesn't know about getNextAvailableSpot method, so the compiler gives you warning.
ReplyDeleteThe code runs fine because _truckLayer is a pointing to correct TruckLayer, which knows about getNextAvailableSpot.
Simply change your declaration and the warning will be gone.
@interface GameLayer : CCLayer
{
CCSprite *_background;
CCPanZoomController *_controller;
CCLayer *_truckLayer;
}
to
@class TruckLayer;
@interface GameLayer : CCLayer
{
CCSprite *_background;
CCPanZoomController *_controller;
TruckLayer *_truckLayer;
}
Just as the warning says: the compiler can't guarantee that CCLayer has a method to handle the getNextAvailableSpot message. Unless you've somehow added in such a method dynamically, or have some other (very good) reason to believe that this method is present, this is probably a problem.
ReplyDelete