Sprite Kit pause/resume scene isn't working after restart - ios

Question

I have a game where I've successfully implemented a pause feature when the home button is pressed. In my View Controller that has the main scene, I pause using:
- (void)appWillEnterBackground{
SKView *skView = (SKView *)self.view;
skView.paused = YES;
bubbleOn=NO; //turns bubble spawn off
[[NSNotificationCenter defaultCenter] removeObserver:self];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(appWillEnterForeground)
name:UIApplicationDidBecomeActiveNotification
object:NULL];
}
To unpause,
- (void)appWillEnterForeground{
SKView * skView = (SKView *)self.view;
skView.paused=NO;
bubbleOn=YES; Allows recursive method to run until bubbleOn = YES
[NSTimer scheduledTimerWithTimeInterval:slowMo target:scene selector:#selector(spawnNew) userInfo:nil repeats:NO]; //Recursive spawn method
[[NSNotificationCenter defaultCenter] removeObserver:self];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(appWillEnterBackground)
name:UIApplicationWillResignActiveNotification
object:NULL];}
This works well until my the game ends and a new scene (End Scene) is presented. After the End Scene shows a score, the user can tap again to start again and main scene is presented. The main scene's initWithSize method begins the recursive method spawnNew. If the app goes to the background, the scene pauses and spawnNew stops.
But when the app goes to foreground, the scene does resume, but the spawnNew method does not work. It gets called and outputs a correct NSLog message, but the the method doesn't spawn bubble nodes.
The spawnNew method is in my main scene's implementation:
-(void) spawnNew{
if (bubbleOn==YES){
bubble = [SKSpriteNode spriteNodeWithImageNamed:ballName];
bubble.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:bubble.size.width/2];
...
//bubble properties
...
[self addChild:bubble];
NSLog(#"Spawn!");
[NSTimer scheduledTimerWithTimeInterval:slowMo target:self selector:#selector(spawnNew) userInfo:nil repeats:NO];
return;
} else{
return;
}
I'm out of ideas at this point! Any suggestions?

Answer 1

The easiest way is to get rid of NSTimer. You can use SKAction instead.
In SKScene's initWithSize method:
- (instancetype)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
....
__weak GameScene *weakSelf = self;
SKAction *spawnBubble = [SKAction runBlock:^{
[weakSelf spawnNew];
}];
SKAction *wait = [SKAction waitForDuration:slowMo];
[self runAction:[SKAction repeatActionForever:
[SKAction sequence:#[spawnBubble,wait]]]];
}
return self;
}
In this case you don't even need to use bubbleOn variable, as scene stops executing any actions as soon as it's SKView is paused.