Pausing across multiple view controllers, what does -> do? - objective-c

Question

a few noobie questions here first time ever I've tried to pause a Scene/Nodes hoping someone can please help me understand what is happening.
I have 2 VC's
GameViewController.m (contains my GameUI related code)
GameScene.m (contains my gameplay related code and my main node called "myWorld").
From GameViewController.m
If I run
_scene.paused = YES;
everything is paused on the screen by the looks of it and nothing moves, but if I unpause the game via
_scene.paused = NO;
you can tell my GameScene.m "myWorld" node has continued to run because when I unpause the game goes into super fast forward and catches up to the position it would have been if I did not pause.
I tried a few other lines like
self.view.paused = YES;
then Xcode suggested that I change to
self->_skView.paused = YES;
When I did this it works! and successfully paused all of the contents including the "myWorld" code inside GameScene.m. But how? I don't understand?
Can someone please tell me what does "->" do here???
Also in my other VC GameScene.m I have a line of code in my update method that is waiting for the game to paused via
if (self.paused==YES)
but when I run this new code from GameViewController.m "self->_skView.paused = YES;"
that if (self.paused==YES) "if" condition is not met inside here.
GameScene.m
-(void)update:(CFTimeInterval)currentTime {
if (self.paused==YES) {
//do stuff
How do I write that the "if" condition so that when GameViewController.m "self->_skView.paused = YES;" the "if" condition is met in GameScene.m?
I guess what I am asking is how do I talk from one VC to the other? Or how do I tell both VC's properly that the game is paused etc?
Any help would be great my code below
GameViewController.m
#implementation GameViewController {
SKView *_skView;
GameScene *_scene;
}
- (void)viewWillLayoutSubviews
{
[super viewWillLayoutSubviews];
if (!_skView) {
_skView =
[[SKView alloc] initWithFrame:self.view.bounds];
GameScene *scene =
[[GameScene alloc] initWithSize:_skView.bounds.size];
scene.scaleMode = SKSceneScaleModeAspectFill;
[_skView presentScene:scene];
[self.view addSubview:_skView];
[self.view sendSubviewToBack:_skView];
_scene = scene;
__weak GameViewController *weakSelf = self;
}
}
//My pause method
//was
//_scene.paused = YES;
//now
self->_skView.paused = YES;
//My unpause method
//was
//_scene.paused = NO;
//now
self->_skView.paused = NO;
GameScene.m
-(void)didMoveToView:(SKView *)view {
SKNode *myWorld = [SKNode node];
[self addChild:myWorld];
-(void)update:(CFTimeInterval)currentTime {
if (self.paused==YES) {
//do stuff

Answer 1

I suggest you avoid creating an instance variable (ivar) for your SKScene subclass. If you don't set the ivar to nil at some point, SpriteKit won't release the scene when you transition to another scene. Also, you don't need the ivar for the SKView, since you can access it through self. Here's an example of how to pause the SKView from the view controllers and scene subclasses:
In your view controllers,
pause the SKView with
((SKView *)self.view).paused = YES;
and check if the view is paused with
if (((SKView *).self.view).paused) {
// Do something
}
In your SKScene subclasses (e.g., GameScene),
pause the SKView with
self.view.paused = YES;
and to check if the view is paused with
if (self.view.paused) {
// Do something
}
You can use the delegation mechanism to tell a view controller to pause its view or ask a VC if its view is paused.