Background's zPosition
is 1 and emitter node's is 2. Still background is on front. I even tried higher numbers, but it won't help.
Code
SKSpriteNode *bg = [SKSpriteNode spriteNodeWithImageNamed:@"TiltToMove_BG"];
bg.size = self.size;
bg.zPosition = 1;
bg.position = CGPointMake(self.size.width * 0.5, self.size.height * 0.5);
[self addChild:bg];
NSString *fireEmmitterPath = [[NSBundle mainBundle] pathForResource:@"fire" ofType:@"sks"];
SKEmitterNode *fireEmmitter = [NSKeyedUnarchiver unarchiveObjectWithFile:fireEmmitterPath];
fireEmmitter.position = CGPointMake(self.size.width * 0.5, self.size.height * 0.5 - 100);
fireEmmitter.name = @"fireEmmitter";
fireEmmitter.zPosition = 2;
fireEmmitter.targetNode = self;
[self addChild:fireEmmitter];