Crash when instantiating ViewController from Storyboard

Question

I have got a single view in my storyboard, which I add to my current view by doing the following :

MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:@"MainController"];
             [self.view addSubview:mvc.view];

storyboard

The view appears, but everything I do after it appears, leads to a crash. What am I doing wrong ?

Here is an example when it crashes:

-(IBAction)showUsername:(id)sender{

    [testLabel setText:@"username"];

}

Everything is hooked up in storyboard as well, so falsely linked connections should not cause the problem.

you should show your crash log here... – Seamus Feb 05 '12 at 16:27 — Seamus, Feb 05 '12 at 16:27
there is nothing more than a blue "(gdb)" ... – the_critic Feb 05 '12 at 16:30 — the_critic, Feb 05 '12 at 16:30

score 8 · Accepted Answer · answered Feb 07 '12 at 10:30

8

You instantiate a new view controller:

MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:@"MainController"];

But you do not retain it. Your view hierarchy is, as soon you added it to another view.

[self.view addSubview:mvc.view];

So when a button is clicked, a message is sent to you IBAction, but your view controller has been released already. To prevent this from happening, retain your mvc variable, for example somewhere in a property.

@property(nonatomic, strong) MainViewController *controller;

self.controller = mvc;

answered Feb 07 '12 at 10:30

Joris Kluivers

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yes thank you, I asked this question again, and got the same answer... The problem has already been solved, but thank you anyway. I am sure this will help others too. – the_critic Feb 07 '12 at 13:36
Love you <3 debug console doesn't even give a clue to find this out! – Clad Clad Jul 29 '15 at 09:45

score 0 · Answer 2 · answered Feb 05 '12 at 16:33

0

enter image description here

I can think all reason before you show log...

answered Feb 05 '12 at 16:33

Seamus

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I think it gets released or not it is not properly instantiated... But I do not know how to solve it. I assigned it to my controller class, it should work fine. – the_critic Feb 05 '12 at 16:40
@user1066899 you can press ctrl and drag your viewcontroller from ib to your .h file. then all is fine. – Seamus Feb 05 '12 at 16:55

score 0 · Answer 3 · answered Feb 05 '12 at 16:38

0

Turn NSZombie on in the Product>>Edit Scheme you should get more descriptive Error showing then. Then you can add it.

answered Feb 05 '12 at 16:38

Popeye

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Yeah thank you that works fine. Now I finally get the error, and as I assumed, my ViewController gets deallocated `-[MainViewController performSelector:withObject:withObject:]: message sent to deallocated instance 0x3fa5a60` – the_critic Feb 05 '12 at 16:54

score 0 · Answer 4 · answered Feb 05 '12 at 16:41

0

Make sure your method is declared and implemented correctly. Also make sure you have IBOutlet UILabel * testLabel in your .h. The only other problem I can think of other than that is how you hooked it up. Does it only crash when you press the button?

answered Feb 05 '12 at 16:41

Seany242

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score 0 · Answer 5 · answered Feb 07 '12 at 10:16

This line is wrong this will be why you are getting the error.

MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:@"MainController"];
         [self.view addSubview:mvc.view];

replace it with this

 MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:@"MainController"];
[self presentModalViewController:mvc animated:YES];

In storyboards you are not adding a subview you are doing one of three things presenting a modal, pushing it on to the navigation controller stack or making a custom one of these.

The addsubview is reserved for when the viewcontrolle has been presented. — Popeye, Feb 07 '12 at 10:19

Crash when instantiating ViewController from Storyboard

5 Answers5

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