ARC ViewController gets deallocated - ios

Question

I have a view controller that displays a button. When I click the button, the corresponding selector needs to be called. However, with ARC, the application crashed with an EXC_BAD_ACCESS message.
-(IBAction)reseauPushed:(id)sender{
self.reseauVC = [[ReseauVCIpad alloc]initWithNibName:#"ReseauVCIpad" bundle:nil];
[self.viewCenter addSubview:self.reseauVC.view];
}
with
#property (strong, nonatomic) ReseauVCIpad *reseauVC;
and the crash log :
-[ReseauVCIpad performSelector:withObject:withObject:]: message sent to deallocated instance
I use ARC.
The button action :
-(IBAction)helloPushed:(id)sender{
NSLog("hello);
}

Answer 1

This ReseauVCIpad view controller is obviously getting deallocated some how. Either you accidentally are setting self.reseauVC to nil somewhere, or, more likely, the parent view controller, itself, is somehow getting deallocated. Is there any chance you did this addSubview technique for any of the preceding view controllers? And if not, how did you instantiate the root view controller?
To diagnose where the problem is, I'd suggest you add dealloc methods to all of your various view controllers so that you can confirm if any are getting deallocated prematurely. (Either set breakpoints or put in NSLog statements.) I'd wager you're seeing the parent of ReseauVCIpad getting deallocated, which is, in turn, allowing ReseauVCIpad itself to be deallocated.
By the way, as others have pointed out, the typical answer to this problem is to make sure you're doing the appropriate containment calls (show below), or if this child view controller takes up the whole screen, you should just be pushing to it or modally presenting it. Clearly, you have a strong reference to ReseauVCIpad, so the lack of containment calls isn't the source of the problem with ReseauVCIpad itself (though I wonder if you are doing this addSubview trick without containment calls with one or more of ReseauVCIpad's parent view controllers).
But you still should be doing these containment calls (or do a proper modal/push transition), regardless, to ensure your view controller hierarchy stays in sync with your view hierarchy (see WWDC 2011 video Implementing UIViewController Containment for lengthy discussion of why this is important). The appropriate containment calls for adding a subview with its own controller is, at a minimum, as follows:
- (IBAction)reseauPushed:(id)sender
{
self.reseauVC = [[ReseauVCIpad alloc]initWithNibName:#"ReseauVCIpad" bundle:nil];
[self addChildViewController:self.reseauVC];
[self.viewCenter addSubview:self.reseauVC.view];
[self.reseauVC didMoveToParentViewController:self];
}
For a more detailed description, see the video I referenced above, or see the Creating Custom Container View Controllers section of the View Controller Programming Guide for iOS.
And when you want to remove it, you should do the appropriate containment calls there, too:
- (void)removeReseau
{
[self.reseauVC willMoveToParentViewController:nil];
[self.reseauVC.view removeFromSuperview];
[self.reseauVC removeFromParentViewController];
self.reseau = nil;
}
This generally solves this issue (where the child view controller was deallocated). It won't solve your reseauVC problem (because you already have strong reference), but (a) you should do this wherever you do addSubview with a view controller, regardless; and (b) I show you the pattern in case you're doing addSubview elsewhere without maintaining a strong reference.

Answer 2

Several things. You should not add one view controller's content view to another view controller unless you set up a parent/child view controller relationship. This was added in iOS 5, and expanded in iOS 6 (and probably further expanded in iOS 7...) Look at methods like addChildViewController:, removeFromParentViewController, isMovingToParentViewController, and didMoveToParentViewController:
The easiest way to set up a parent/child view controller relationship is to use storyboards (which requires iOS 5) and an embed segue. (Which I believe was added in iOS 6). That takes care of all the housekeeping for setting up parent/child view controller relationships for you.
Your second view controller is being saved to a strong property, so I'm not clear on why it's being deallocated. I'm also not clear where the call to performSelector:withObject:withObject: is coming from. What source line is crashing, and are you using performSelector:withObject:withObject: in your code anywhere?