Error when trying to use a text view outside of view controller

Question

I'm getting the error:

Fatal error: unexpectedly found nil while unwrapping an Optional value

whenever I try adding text to a text view (bottomTextView) outside of my view controller. My text view is linked to my main view controller. I have another class called Checkbox (subclass of UIButton) that tries to add text to the text view using:

var main_vc = ViewController()
main_vc.bottomTextView.insertText("Checked")

However, I have no problem using the following inside my view controller:

bottomTextView.insertText("Checked")

I can't figure out why this is and how to fix it. Thanks!

EDIT:

My Checkbox class is a subclass of UIButton that has a method that is called whenever a checkbox is clicked. When that checkbox is clicked I want to add text to the text view inside my main view controller.

Answer 1

You do not have view initialized. My guess is you are creating if from a nib file and that is why you need to initialize it like this

var main_vc = ViewController(nibName: "ViewController", bundle: nil)

When you try to access is without the view, the IBOutlets are nil since they are not connected to anything. That is why you are getting that error.

The second thing works because all of the methods exist in your ViewController object but there is no view to control it.

If you have used the Storyboard to create the file, you would first need to set an identifier for that ViewController like this

And then create your ViewController like this

let storyboard = UIStoryboard(name: "Main", bundle: nil) // Or what ever your storyboard file name is
let main_vc = storyboard.instantiateViewControllerWithIdentifier("PublishView") as! ViewController // What you name your view controller

Answer 2

If you are using Storyboard then;

var storyboard = UIStoryboard(name: "Main", bundle: nil)
var main_vc = storyboard.instantiateViewControllerWithIdentifier("ViewControllerIdentifier") as! ViewController
main_vc.bottomTextView.insertText("Checked")

Answer 3

I suspect your problem is you're trying to access bottomTextView, from another view controller, before you've presented the view controller (with a segue for example). In that case none of your ViewController's IBOutlets have been set and so you're getting that error.

I think you're thinking about this in the wrong way though - a view controller shouldn't directly edit another view controller's view. Instead, you could set the text, that should appear in bottomTextView, in prepareForSegue. For example, say this was your ViewController class:

class ViewController : UIViewController {
    var yourText: String = ""
    @IBOutlet var bottomTextView: UITextView!

    override func viewDidLoad() {
        // In viewDidLoad all the outlets have been set so you won't get any errors
        // setting the text.
        bottomTextView.text = yourText
    }
}

And this was another view controller you wanted to move from, to an instance of ViewController:

class AnotherViewControler : UIViewController{
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if let vc = segue.destinationViewController as? ViewController 
           where segue.identifier == "YourSegueID" {

            vc.yourText = "SomeText"
        }
    }
}

For more information on passing data between view controllers, have a look at this question: How do you share data between view controllers and other objects in Swift?