Why is my array property being discarded after method execution?

Question

Edit: the first answer has guessed it is because I am not using a protocol to "pass data backwards." I am currently implementing that and we'll see if it fixes it.

I'm very new to iOS/objective-C. I have this property on my class:

@interface GameController

@property (strong, nonatomic) NSMutableArray* targets;

@end

I was then using addObject on the array in the body of one of the GameController methods, and it didn't throw any errors, so I thought it was okay until I checked [_targets count] at the end of that method and found it was zero. So I initialized it at the beginning of that method:

if(self.targets == nil){
    self.targets = [[NSMutableArray alloc] init];
}

And then count was 6. But as soon as I go to read self.targets in a different method, it's back to zero. Why is that happening? What am I doing wrong with initializing this?

Edit: Interestingly, in the other method, if I check, it is no longer nil-- it has been initialized. But it is nonetheless empty. Very confused!

Edit2: Okay, I've uploaded the code to pastebin, having cut out irrelevant stuff as much as possible.

So drawMainControls gets called first, when the app loads, and it draws a bunch of TileViews and TargetViews, instantiating self.targets in the process. Each TileView has a GameController property which is assigned to be the main GameController immediately after instantiation.

The TileView detects taps and calls addPossibleLetter on its controller. addPossibleLetter is the method that checks the self.targets array and comes up empty-handed.

Here is the GameController.h file: http://pastebin.com/C30Mi2LL

Here is the GameController.m file: http://pastebin.com/cvf2WmBs

Here is the TileView.m file: http://pastebin.com/gehJGYBD

Are you sure you're dealing with the same instance in both cases? Log the `self` pointer using the `%p` format specifier in both places. — Ken Thomases, Nov 26 '14 at 06:34
Checked, verified. Same instance. Good thought though! Didn't know about the `%p` format specifier yet. — temporary_user_name, Nov 26 '14 at 06:40
Yes. And I just changed it so it's a public `@property` in the header file and changed everything to use `self.targets`, no difference, same exact problem. Just tweaking random things since I'm not sure what to look into. — temporary_user_name, Nov 26 '14 at 06:57
@KyleEmmanuel one minute....see if I can reasonably do that. — temporary_user_name, Nov 26 '14 at 06:58
@KyleEmmanuel it is done...hopefully it's enough that something jumps out at someone's more experienced eyes. It all seems right to me but something is obviously awry. — temporary_user_name, Nov 26 '14 at 07:33
@Aerovistae are you sure you do not pass `nil` or an empty string as `drawMainControlsForWord:` parameter? In other words, are you sure `for (int i = 0; i < length; i++)` loop is fired at least once? — Bartek Chlebek, Nov 26 '14 at 07:41
@BartekChlebek I think Krishna got it...I have to use a protocol. At least...I think. And yes, definitely sure about that part. — temporary_user_name, Nov 26 '14 at 07:48

score 1 · Accepted Answer · edited May 23 '17 at 10:33

1

There are fair chances that you are calling the other method before the method in which this method is being initialized. I guess when passing data backward the way you are doing you are properly aware of using protocols and delegates. You can have look at his link which explains this concept very clearly. Passing Data between View Controllers

edited May 23 '17 at 10:33

Community

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answered Nov 26 '14 at 06:45

Krishna

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No, the first is done as part of viewDidLoad, the second is done as a reaction to a tap event. – temporary_user_name Nov 26 '14 at 06:53
and the second method is on the same self.i.e. both the methods are in the same controller? – Krishna Nov 26 '14 at 06:59
could you please add some more code so that I can get what's actually going on? – Krishna Nov 26 '14 at 07:03
I'm trying to figure out how I can do that...there's a lot of code. – temporary_user_name Nov 26 '14 at 07:08
you just paste code for both the methods and code of any intermidiate method you are calling before getting count for _targets. – Krishna Nov 26 '14 at 07:12
So I guess when passing data backward the way you are doing you are properly aware of using protocols and delegates. You can have look at his link which explains this concept very clearly. http://stackoverflow.com/questions/5210535/passing-data-between-view-controllers – Krishna Nov 26 '14 at 07:46
Ohhhh I have to use a protocol for this? Ohhh....include this in your answer so I can accept it. – temporary_user_name Nov 26 '14 at 07:47
Well, let me try to implement it first and see if that's right. – temporary_user_name Nov 26 '14 at 07:52
You got it, that was it. Thanks. – temporary_user_name Nov 30 '14 at 04:51

Why is my array property being discarded after method execution?

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