Question

Based on my reading around, I have learned that I need to set a variable in my AppDelegate that references my view controller so that I can do things like this. Receive a barcode scan and subsequently call a method in a controller and pass in that barcode scan. So I have this in my AppDelegate.

- (void)BarcodeDataArrived:(char *)BarcodeData;
{
[myViewController LoadBarcodePage:BarcodeData];
}

I know that this method is being called when my bluetooth scanner scans a barcode. The problem is that myViewController object is not referencing the current view controller and as a result all the objects are null.

I don’t think I want to create a new instance of myViewController since the storyboard is already creating an instance of it when the app loads. I just want to be able to reference the same object that the storyboard is creating. So, if I am understanding things correctly, I need to do something like this in my AppDelegate to set the variable:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:  (NSDictionary *)launchOptions
{

    // I Want To Set A Reference To My View Controller Here Such As...   

    myViewController = aViewController;

    // Where aViewController Is What The Storyboard Initialized.

    return YES;
}

How would I do this. All the references I have found on the NET seem to involve nibs and not storyboards.

This is my first app. Help please!

Answer 1

You shouldn’t implement that in your App Delegate.
Why don’t you try to implement your BarcodeDataArrived in a ViewController then

- (void)BarcodeDataArrived:(char *)BarcodeData {
   [self performSegueWithIdentifier:@"toMyViewControllerSegue" 
                             sender:self];

    }

Then in the prepareForSegueMethod you can send data to the destination Controller

 -(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
 myViewController *destinationController= (myViewController * )segue.destinationViewController;

    destinationController.BarcodeData=BarcodeData;

  }

Now if you don’t want to change the view then you have to try another approach, myViewController should be an object ( or class) and implement the method LoadBarcodePage in there. You could have the object in the delegate and it can be referenced in any class by using

 AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
 [delegate.myVar doWhatever you want];