Cocos2D: Get layer's position in scene from another class

问题

I'm trying to retrieve the current position of the layer added as a child in a scene while a scene transition is occurring. The transition is an edited Cocos2D transition that slides the layer off the screen while a new one appears. I created my own implementation inside CCActionEase with an update method:

#import "JoinedMapsScene.h"
#import "JoinedMapsLayer.h"

    @implementation CCEaseInWithPercentMult
    -(void) update: (ccTime) t
    {

        [other update: powf(t,rate)];

        CCScene * scene = [[CCDirector sharedDirector] runningScene];

        CCNode* layer = [scene getChildByTag:0];

        NSLog(@"% .2f",layer.position.x); //returns 0 
        NSLog(@"% .2f",layer.position.y); //returns 0 
    }

However these return 0 when the transition occurs. Presumably because I'm getting the position relative to itself?

EDIT:

I found out this will not work. I've correctly accessed my current scene by pointing to the right class by doing this:

JoinedMapsScene * scene = (JoinedMapsScene *)[[CCDirector sharedDirector] runningScene];

And calling my supposed method by doing this:

[scene getJoinedMapsLayerPosition];

To my surprise, while the transition is happening, the current runningScene is my transition class!

It gives my this exception: -[ExitLTransition getJoinedMapsLayerPosition]: unrecognized selector sent to instance 0x5e4e20

I need to figure out an alternate way of doing this.

回答1:

Add this in AppDelegate.h :

@class CCLayer;

@interface AppController : NSObject <UIApplicationDelegate, CCDirectorDelegate,UIGestureRecognizerDelegate>
{
    CCLayer             *mCurrentLayer;

}

@property (nonatomic, retain) CCLayer *currentLayer;

Add this in AppDelegate.mm :

@implementation AppController
@synthesize currentLayer = mCurrentLayer;

In your Layer init class use this. In all scene method.

@implementation MyMainMenu

+(CCScene *) scene
{
    // 'scene' is an autorelease object.
    CCScene *scene = [CCScene node];

    // 'layer' is an autorelease object.
    MyMainMenu *layer = [MyMainMenu node];

    AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];
    app.currentLayer = layer;

    // add layer as a child to scene
    [scene addChild: layer];

    // return the scene
    return scene;
}

You can check anywhere in project..

 AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];

 if([app.currentLayer  isKindOfClass:[MyMainMenu class]])
 {
     MyMainMenu *mm = (MyMainMenu*) app.currentLayer;
     [mm calFunction]; 
 }

来源：https://stackoverflow.com/questions/12754390/cocos2d-get-layers-position-in-scene-from-another-class

标签

cocos2d-iphone

position

layer

scene