Problem adding objects to NSMutableArray

Magoolah · August 2011

I am having problems adding objects to my NSMutableArray. It seems that something gets added (object count increases by 1 in debugger), but the only thing added is a 0x0 (null) instead of the address of an object. I've read through everything somewhat relevant that I could find, but I couldn't find anything that seemed to answer this issue. Most related posts seem to revolve around memory management, but the solution is not jumping out at me.

I appreciate any help you can provide.

I've included what I think are the relevant parts of the code. Please tell me if you need to see anything more.

Within GamePlayView.h

@interface GamePlayView : UIViewController {

    Player *gamePlayer;
    NSMutableArray *boardObjects;

}

@property (retain, nonatomic) Player *gamePlayer;
@property (retain, nonatomic) NSMutableArray *boardObjects;

@end

Within GamePlayView.m

- (void)viewDidLoad {

    // Create player

    Player *tempPlayer = [[Player alloc] initWithFrame: self.view.frame];
    if (tempPlayer == NULL) {
        NSLog(@\"GamePlayView viewDidLoad: null Player\");
    }
    else self.gamePlayer = tempPlayer;

    // Create array of board objects

    NSMutableArray *newArray = [[NSMutableArray alloc] init];

    self.boardObjects = newArray;
    [self.boardObjects addObject: gamePlayer];  // First breakpoint here
    topObject = 0;

    BoardObject *mine = [[BoardObject alloc] initWithFrame: self.view.frame];

    [self.boardObjects addObject: mine];  // Second breakpoint here
    topObject = 1;

    [super viewDidLoad];

} // End viewDidLoad

I put breakpoints at the addObject lines (commented in code). When execution stops at the first breakpoint, the debugger shows a good tempPlayer, and a good gamePlayer (both non-null, with the same address). It shows 0 objects in boardObjects, like this:

boardObjects = (_NSArrayM *) 0x4b22080 0 objects

When I step over this breakpoint, the debugger shows 1 object in boardObjects, as follows:

boardObjects = (_NSArrayM *) 0x4b22080 1 objects
0 = (NSObject *) 0x0

When I continue program execution, and the debugger stops at the next breakpoint, I also see a good mine object, with boardObjects still described as above. After stepping over this breakpoint, boardObjects now looks like this:

boardObjects = (_NSArrayM *) 0x4b22080 2 objects
0 = (NSObject *) 0x0
1 = (NSObject *) 0x0

baja_yu · August 2011

You are leaking objects all over the place. You never release 'tempPlayer', 'newArray' or 'mine'.

Also, in viewDidLoad the call to super should come before all other code.

BrianSlick · August 2011

Add this at the end of the method:

NSLog(@\"self.boardObjects is: %@\", [self.boardObjects description]);

Are you experiencing an actual problem in your app - which you didn't describe - or are you merely concerned about what you're reading from the debugger?

Magoolah · August 2011

baja_yu: The releases are in the code, I just didn't show them. Thanks for the tip on moving the call to super to the top. I did that, with no change to what I was observing.

Brian: I was surprised to see that your NSLog revealed actual contents in the boardObjects array! Thank you. I suppose I had no problem after all.

However, I put a breakpoint at the NSLog line, and the debugger still shows 0x0 for each array entry, both before the NSLog line, and after it executes. Does this mean I'll never be able to get to array contents directly in the debugger?

To your question, I hadn't tried to proceed past this point in my app yet. I'll eventually be dynamically adding and removing hundreds of objects to this array, and I needed it to work properly before proceeding.

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