zPosition World Layers

layers.m

/* The layers in a scene. */
typedef enum : uint8_t {
	WorldLayerGround = 0,
	WorldLayerBelowCharacter,
	WorldLayerCharacter,
	WorldLayerAboveCharacter,
	WorldLayerTop,
	kWorldLayerCount
} WorldLayer;

/* Later in the scene initialization */
_layers = [NSMutableArray arrayWithCapacity:kWorldLayerCount];
for (int i = 0; i < kWorldLayerCount; i++) {
    SKNode *layer = [[SKNode alloc] init];
    layer.zPosition = i - kWorldLayerCount;
    [_world addChild:layer];
    [(NSMutableArray *)_layers addObject:layer];
}