SPEventListener.m EXC_BAD_ACCESS

iosNighthawk

Hey everyone I'm getting a bad access in SPEventListener.m initWithTarget.
Tested Devices:
iPhone 4 with iOS 6
iPad Mini with iOS 7

screen shot of stack trace
http://www.levieggert.com/sparrow/SPEventListener_EXC_BAD_ACCESS.png

I'm testing on the very latest from Master in which I pulled a few days ago.

I tested on both 2.0 and 2.0.1 and the crash doesn't occur.
It does occur on Sparrow S and latest Master.

Any ideas why this could be?

- (instancetype)initWithTarget:(id)target selector:(SEL)selector
{
    __block id weakTarget = target;

    return [self initWithTarget:target selector:selector block:^(SPEvent *event)
            {
                objc_msgSend(weakTarget, selector, event);//EXC_BAD_ACCESS
            }];
}

The crash occurs when my game screen is exited and torn down via my player colliding with a game object that will cause the game to end.

If I just exit the game via SPButtonTouch I never see the crash.

I'll spend some more time looking into the crash and keep you posted.

I also want to say I am really happy with Sparrow and MRC. This game would not be possible with out it. I was making a long decision to switch to Cocos2D-x until I came across Rob's post with Sparrow S and MRC. So I gave it a whirl and I now I regret even thinking about switching!

My FPS literally went from averaging 25fps to now running closer to 60fps. And thats on iPhone 4.

So thank you all for your hard work in making Sparrow great!

iosNighthawk

I'm thinking the main reason for this crash is because I'm shutting down and deallocating all my Sparrow objects mid update.

I know this same scenario would cause me problems if I was looping forward through an array of objects and one was removed while looping. Looping an array in reverse protects against this.

So what I'm thinking to do for a quick bandaid is shutdown my game with a SPTween. Shouldn't that allow sparrow update to finish and then that tween would start up and complete at beginning of update cycle?

I tested and it does appear to be the case. Haven't seen a crash.

SPTween *tween = [SPTween tweenWithTarget:self time:0.1];
    [Sparrow.juggler addObject:tween];

    __weak CGameViewController *weakSelf = self;
    tween.onComplete = ^{
        [weakSelf stop];//stop game
    };

Daniel

Hi Nighthawk,
sorry for my late reply! I allowed myself a few offline days after New Year's Eve. 😉

First of all, I'm happy to hear that the new version of Sparrow helped your performance that much — that's awesome! I'm really thankful to Robert for making that switch back to MRC.

As for the crash:

The crash happens when Sparrow dispatches "ENTER_FRAME" events to all display objects. You must have an event listener on an object of which the "target" has already been freed. Could that be? You write that you are "deallocating all your Sparrow objects mid update" — so it sounds reasonable.

It might have worked in the past simply because ARC holds on to the object longer than what's done with MRC. (Which is, incidentally, one reason why ARC is so much slower; but it avoided some of those troubles.)

iosNighthawk

Hey Daniel welcome back! Glad to hear you took some time off, I'm sure you've been very busy.

And you are absolutely right. When that collision occurs mid update the game is completely removed from memory along with those enter frame events. That definitely explains why the crash would occur and why it wouldn't be a bug on your end.

Thanks!