When my UIViewController accesses an NSArray in my AppDelegate from an IBAction it crashes the progr

Posted by JasonClark on Stack Overflow See other posts from Stack Overflow or by JasonClark
Published on 2010-05-10T14:00:45Z Indexed on 2010/05/10 14:04 UTC
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I have a couple UIViewControllers that I am trying to access an array inside my AppDelegate. When I use an IBAction UIButton and in that method I access my AppDelegate my program dies silently. Nothing in output or the debugger, it just stops. If I run it several times I can see that it is failing to access the array properly.

To investigate this problem I created a very basic app.

In my AppDelegate.h I declared and set properties for the array

#import <UIKit/UIKit.h>
@class MyViewController;
@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
    UIWindow *window;
    MyViewController *viewController;
    NSArray *images;
}
@property (nonatomic, retain) NSArray *images;
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet MyViewController *viewController;`

In the AppDelegate.m I synthesised and initialized the NSArray (Also made sure the images were added to the Resources folder).

@synthesize images;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
    images = [NSArray arrayWithObjects:
        [[NSBundle mainBundle] pathForResource:@"bamboo_nw" ofType:@"jpg"],
        .....
        nil];
    NSLog(@"init images size:%i",[images count]); 
    [window addSubview:viewController.view];
    [window makeKeyAndVisible];
    return YES;
}

In my UIViewController.h I added class, imported header file, declared, and set properties for my AppDelegate pointer.

#import <UIKit/UIKit.h>
#import "MyAppDelegate.h"
@class MyAppDelegate;
@interface MyViewController : UIViewController {

MyAppDelegate *mainDelegate; IBOutlet UIButton mybutton; } @property (nonatomic, retain) MyAppDelegate mainDelegate; @property (nonatomic, retain) UIButton *mybutton; -(IBAction) doSomething;`

In my UIViewController.m I synthesize and assign my AppDelegate. I set up an IBAction that will log the same count of the NSArray from the AppDelegate.

#import "MyViewController.h"
#import "MyAppDelegate.h"
@implementation MyViewController
@synthesize mybutton;
- (void)viewDidLoad {
    mainDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
    NSLog(@"vdl images size:%i",[mainDelegate.images count]);
    [super viewDidLoad];
}
-(IBAction) doSomething {

NSLog(@"ds images size:%i",[mainDelegate.images count]); }

I print the size of the NSArray in the AppDelegate when I create it, in the ViewController when I first assign my AppDelegate pointer, and then as a result of my IBAction.

I find that everytime I hit the button the program dies. On the third time I hit the button, I saw that it ran my IBAction but printed my array size as 1 instead of 8. Am I missing something? Also, why don't I get stack traces or anything, the debugger just dies silently?

Thanks in advance for any help!

Debugger Console output for 3 runs:

[Session started at 2010-05-10 06:21:32 -0700.]
2010-05-10 06:21:44.865 My[59695:207] init images size:8
2010-05-10 06:21:47.246 My[59695:207] vdl images size:8

[Session started at 2010-05-10 06:22:15 -0700.]
2010-05-10 06:22:18.920 My[59704:207] init images size:8
2010-05-10 06:22:19.043 My[59704:207] vdl images size:8

[Session started at 2010-05-10 06:22:23 -0700.]
2010-05-10 06:22:25.966 My[59707:207] init images size:8
2010-05-10 06:22:26.017 My[59707:207] vdl images size:8
2010-05-10 06:22:27.814 My[59707:207] ds images size:1

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