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I have a View Controller class which contains a button property, and I need to change its enabled stated from a different class (Table View Controller). I'm also calling a method that's in that VC class. I can call the method just fine, but when I try to access the button property, it's nil. Actually all of its properties are nil. I must have something not set up quite right.

//ViewController.h
@property (strong, nonatomic) IBOutlet UIButton *aButton;
- (IBAction)myButtonTapped;

//ViewController.m
//did not override setter or getter for aButton
- (IBAction)myButtonTapped {
     //code here
}

//Table VC.m
@property (strong, nonatomic) ViewController *myVC;

- (ViewController *)myVC {
    if (!_myVC) _myVC = [[ViewController alloc] init];
    return _myVC;
}

- (void)userEnteredText:(NSNotification *)notification {
     [self.myVC myButtonTapped]; //runs method without issue
     self.myVC.aButton.enabled = YES; //does not occur since aButton is nil - myVC is not nil
}
Jordan H
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  • possible duplicate of [Passing Data between View Controllers](http://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) – Hot Licks Mar 31 '14 at 02:01
  • I'm not passing data between VCs but rather just changing the button enabled state from a different class. Both VCs are actually on screen at the same time - the table VC is inside a container view which is inside the original VC. – Jordan H Mar 31 '14 at 02:16
  • Sorry, the dupe still applies -- view controller or not has nothing to do with it. Study it. – Hot Licks Mar 31 '14 at 02:23

1 Answers1

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You need to study the information provided by @Hot Licks to understand how to keep references between your objects, but I can tell you that part of your problem is your getter method -

- (ViewController *)myVC {
    if (!_myVC) _myVC = [[ViewController alloc] init];   //  <-- This is a problem
    return _myVC;
}

If your _myVC variable is nil then your getter method allocates a new ViewController - so you won't get a reference to the existing viewController. As you then call the plain init method for your new viewController none of its properties will be initialised - so you get nil for your button.

You don't need to write any code for a simple property like this - the default code that is created for you is all you need. What you do need to do is set the myVC property from your current viewController instance. So somewhere in your viewController you will have

tableVC.myVC=self;

You will need to do this somewhere where you have a reference to your tableVC - so this could be inprepareForSegue if you are using storyboards and segues or wherever you present or push the table vc if you aren't

Paulw11
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