Why is my IBOutlet released under ARC?

Question

Problem

IBOutlet is released before I have the opportunity to use it.

What I want

I want to access the navigation controller from my application delegate so that I can reload the table view.

My setting

I have:

• A Main.xib, which is set as the main interface in the target settings
• IBOutlet for navigation controller as ivar for my application delegate
• This IBOutlet connects to the correct navigation controller in Main.xib
• App Delegate is created in xib but not set as File Owner

I am using ARC, Xcode 4.3.2 and iOS5.1

What i tried

• Change Deployment Goal
• Putting a breakpoint on dealloc for the navigation controller, application delegate - they are never called
• Reading everything I can find on ARC and IBOutlets - nothing contradicts what I do.
• Creating a new project with the minimum required classes - I see exactly the same problem

the code

KPAppDelegate.h

@interface KPAppDelegate : UIResponder <UIApplicationDelegate> { IBOutlet KPBrowseExpensesNavigationController *nc; } @property (strong) IBOutlet KPBrowseExpensesNavigationController *nc; 

KPAppDelegate.m

 @implementation KPAppDelegate @synthesize nc; -(void)setNc:(KPBrowseExpensesNavigationController *)nc_ { nc = nc_; // This gets called on view load and nc gets set. } ...snip... // This is called about 5 seconds after app startup -(void)objectLoader:(RKObjectLoader *)objectLoader didLoadObjects:(NSArray *)objects { // By the time we get here, nc is nil. UITableViewController *tvc = [[nc viewControllers] objectAtIndex:0]; [[tvc tableView] reloadData]; } @end 

UPDATE

I have to do something really stupid here. Even an incredibly simple project still shows this problem. See the link below.

Download a simple test project that shows the problem.

Answer 1

In the nib window, set the FilesOwner class as UIApplication, and then specify the delegate from Outlets to the AppDelegate object. This is what is wrong in your sample project.

Answer 2

Is your way out of the interface builder set as the type KPBrowseExpensesNavigationController ? If not, this will not create a connection between your nib and ViewController.

You must set your custom class as KPBrowseExpensesNavigationController in the Identity Inspector

Answer 3

I'm not sure why you declare it as a property and a non-property. I should do something like this:

 @interface KPAppDelegate : UIResponder <UIApplicationDelegate> @property (nonatomic, strong) IBOutlet KPBrowseExpensesNavigationController *nc; 

And in your implementation:

 @implementation KPAppDelegate @synthesize nc = _nc; // So you don't accidentally use nc ...snip... // This is called about 5 seconds after app startup -(void)objectLoader:(RKObjectLoader *)objectLoader didLoadObjects:(NSArray *)objects { // By the time we get here, nc is nil. UITableViewController *tvc = [[**self.nc** viewControllers] objectAtIndex:0]; [[tvc tableView] reloadData]; } @end 

Hope this helps!

Answer 4

I have not seen where you assign your navigation controller. Just declaring a property will not assign it any value, so it will be zero. You have -didFinishLaunchingWithOptions in the application deletion set the alloc / init statement. Everything else looks good.

 KPBrowseExpensesNavigationController *nc = [[KPBrowseExpensesNavigationController alloc] init]; 

If you have a custom init, you can also use it, but just be sure to configure it before trying to use it.