iOS 7 SpriteKit Game - error saving loading game: 'Attempted to add nil node to parent: name:'(null)'

Question

I'm creating a unscramble words game.

I've reached the stage where I can save/load the game using:

(void)encodeWithCoder:(NSCoder *)aCoder
(instancetype)initWithCoder:(NSCoder *)aDecoder

When I save / load the game the first time there's no problem. When I press the home button the second time the app crashes & I end up with an error that I don't know how to understand.

What does this mean?

2014-01-11 18:23:12.254 GameTest[16622:70b] Terminating app due to uncaught exception

'Attemped to add nil node', reason: 'Attemped to add nil node to parent: <SKNode> name:'(null)' position:{0, 0} accumulatedFrame:{{inf, inf}, {inf, inf}}'

I don't know where the error occurs in my code.

Cheers Luke

it means addChild was called with parameter being nil. Add xcode exception breakpoint, if the error is in your code it'll show you — CodeSmile, Jan 11 '14 at 09:07

score 0 · Answer 1 · answered Jan 12 '14 at 08:08

Thanks LearnCocos2D,

The error is arcane (my view) in it's details.

The problem was in how I dealt with the "bodyWithEdgeLoop" boundary.

The problem was also to do with:

(void)encodeWithCoder:(NSCoder *)aCoder

and

(instancetype)initWithCoder:(NSCoder *)aDecoder

methods.

I'm using Ray Wenderlich's iOS Games by Tutorials book & I made a mistake in the "initWithCoder" method.

I had removed & replaced the edge loop body in the "encodeWithCoder" method, but hadn't created it in the "initWithCoder" method.

So that is the solution. When saving a game the edge body loop must be removed & replaced in the "encodeWithCoder" method, but also has to be created in the "initWithCoder" method.

The biggest problem is that Xcode didn't point to any line in my code. I just did this on a "hunch".

Hope it helps.

score 0 · Answer 2 · answered Mar 31 '14 at 17:31

I've ran into a similar issue that seems to affect some types of iPad. The scene was trying to add nil child.

Adding an exception handling block seems to have fixed it, even though I never see exception print statement.

    @try {
        [self addChild:node];
    }
    @catch (NSException *exception) {
        NSLog(@"Exception adding node :%@",[exception description]);
    }
    @finally {

    }

iOS 7 SpriteKit Game - error saving loading game: 'Attempted to add nil node to parent: name:'(null)'

2 Answers2