Question

I get an error when running my code. The culprit is me accessing a string from a plist below:

    NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
    NSLog(@"%@",sImageFile);

I have this in my cocos2d Init shown here:

-(id) init
{
    // always call "super" init
    // Apple recommends to re-assign "self" with the "super" return value
    if( (self=[super init])) {

        NSUserDefaults *sud = [NSUserDefaults standardUserDefaults];
        NSString *ctlLang = [sud valueForKey:@"ctlLang"];
        NSNumber *questionState = [sud valueForKey:@"questionState"];
        NSNumber *scoreState = [sud valueForKey:@"scoreState"];
        gameArray = (NSMutableArray *)[sud valueForKey:@"gameArray"];
        for (NSString *element in gameArray) {
            NSLog(@"\nQL gameArray value=%d\n", [element intValue]);
        }
        NSString *path = [[NSBundle mainBundle] bundlePath];
        NSString *finalPath = [path stringByAppendingPathComponent:ctlLang];
        dictionary = [NSDictionary dictionaryWithContentsOfFile:finalPath];

        NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
        NSLog(@"%@",sImageFile);
    }
}

The printing of the string works fine in the init section of the scene. The problem occurs in a method I define later. For some reason it is not returning the string in the method shown here:

-(void) checkAnswer: (id) sender {

    CGSize size = [[CCDirector sharedDirector] winSize];
    CCMenuItemSprite *sAnswer = (CCMenuItemSprite *)sender;
    NSLog(@"Checking Answer Tag is ---> %d",sAnswer.tag);
    NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
    NSLog(@"%@",sImageFile);
    if ([question.answer integerValue] == sAnswer.tag) {
        //...
    }
}

What am I missing here? the program bombs at the NSLog statement.

Answer 1

You assign the object returned by dictionaryWithContentsOfFile: to the dictionary ivar but you do not claim ownership of it by sending it a retain message to it:

dictionary = [NSDictionary dictionaryWithContentsOfFile:finalPath];

The method dictionaryWithContentsOfFile: returns an object you do not own. Probably, by the time checkAnswer: is executed the object has already been deallocated. You need to retain it:

dictionary = [[NSDictionary dictionaryWithContentsOfFile:finalPath] retain];

Or use alloc-initWithContentsOfFile: instead, which returns an object you own:

dictionary = [[NSDictionary alloc] initWithContentsOfFile:finalPath];

And the same goes for the gameplay ivar. You do not own the object returned by valueForKey: and you need to retain it. So this line:

gameArray = (NSMutableArray *)[sud valueForKey:@"gameArray"];

should be:

gameArray = [[sud valueForKey:@"gameArray"] retain];