Communicating between Two Layers in a Scene Cocos2d 3

I have two layers set up like so in one scene:

header file for scene:

@interface GameScene1 : CCScene {

GameLayer *gameLayer;

HUDLayer *hudLayer;

}

Main file for scene:

-(id)init {

self = [super init];

if (self != nil) {

gameLayer = [GameLayer node];

[self addChild:gameLayer];

hudLayer = [HUDLayer node];

[self addChild:hudLayer];

}

return self;

}

HUD layer header:

@interface HUDLayer : CCNode {

CCSprite *background;

CGSize screenSize;



}
-(void)updateMonstersSlayed:(NSString*)value;

HUD layer main:

@implementation HudLayer
-(id)init
{
    self = [super init];

    if (self)
    {
        CGSize viewSize = [[CCDirector sharedDirector] viewSize];


        monstersSlayed = [CCLabelTTF labelWithString:@"Monsters Killed: 0" fontName:@"Arial" fontSize:15];
        monstersSlayed.position = ccp(viewSize.width * 0.85, viewSize.height * 0.1 );
        [self addChild:monstersSlayed];


    }
    return self;
}
-(void)updateMonstersSlayed:(NSString*)value
{
    monstersSlayed.string = value;
}

Game Layer main

- (BOOL)ccPhysicsCollisionBegin:(CCPhysicsCollisionPair *)pair collisionPlayer:(CCNode *)user collisionMonster:(CCNode *)monster
{
    if (holdingWeapon)
    {

        HudLayer *myHud = [[HudLayer alloc] init];
        [myHud updateMonstersSlayed:@"Monsters Killed: 1"];

    }
}

Simply trying to get it set to where I can set text from the Game Layer to show up in a Label in the Hud Layer.

How would I accomplish this in Cocos2d 3?

There are many ways you can do this. But for the sake of simplicity the easiest way you can do this is via notifications. For example in the hud add:

@implementation HudLayer

- (void)onEnter
{
    [super onEnter];

    NSNotificationCenter* notiCenter = [NSNotificationCenter defaultCenter];

    [notiCenter addObserver:self
                   selector:@selector(onUpdateMonsterText:)
                       name:@"HudLayerUpdateMonsterTextNotification"
                     object:nil];
}


- (void)onExit
{
    [super onExit];

    [[NSNotificationCenter defaultCenter] removeObserver:self];
}


- (void)onUpdateMonsterText:(NSNotification *)notification
{
    NSDictionary* userInfo = notification.userInfo;

    if (userInfo)
    {
        NSString* text = userInfo[@"text"];

        if (text)
        {
            [self updateMonstersSlayed:text];
        }
        else
        {
            CCLOG(@"Monster hud text param is invalid!.");
        }
    }
    else
    {
        CCLOG(@"Monster hud user info invalid!");
    }
}

@end

Then anywhere in your application where you want to update text you can just post the notification. Using your physics collision began example:

- (BOOL)ccPhysicsCollisionBegin:(CCPhysicsCollisionPair *)pair
    *emphasized text*collisionPlayer:(CCNode *)user collisionMonster:(CCNode *)monster
{
    if (holdingWeapon)
    {
        NSDictionary* userInfo = @{@"text" : @"Monsters Killed: 1"};
        NSString* notiName = @"HudLayerUpdateMonsterTextNotification";

        [[NSNotificationCenter defaultCenter] postNotificationName:notiName
            object:self userInfo:userInfo];

    }
}

Hope this helps.