How to use single storyboard uiviewcontroller for multiple subclass

The code of line we are looking for is:

object_setClass(AnyObject!, AnyClass!)

In Storyboard -> add UIViewController give it a ParentVC class name.

class ParentVC: UIViewController {

    var type: Int?

    override func awakeFromNib() {

        if type = 0 {

            object_setClass(self, ChildVC1.self)
        }
        if type = 1 {

            object_setClass(self, ChildVC2.self)
        }  
    }

    override func viewDidLoad() {   }
}

class ChildVC1: ParentVC {

    override func viewDidLoad() {
        super.viewDidLoad()

        println(type)
        // Console prints out 0
    }
}

class ChildVC2: ParentVC {

    override func viewDidLoad() {
        super.viewDidLoad()

        println(type)
        // Console prints out 1
    }
}

great question - but unfortunately only a lame answer. I don't believe that it is currently possible to do what you propose because there are no initializers in UIStoryboard that allow overriding the view controller associated with the storyboard as defined in the object details in the storyboard on initialization. It's at initialization that all the UI elements in the stoaryboard are linked up to their properties in the view controller.

It will by default initialize with the view controller that is specified in the storyboard definition.

If you are trying to gain reuse of UI elements you created in the storyboard, they still must be linked or associated to properties in which ever view controller is using them for them to be able to "tell" the view controller about events.

It's not that much of a big deal copying over a storyboard layout especially if you only need a similar design for 3 views, however if you do, you must make sure that all the previous associations are cleared, or it will get crashes when it tries to communicate to the previous view controller. You will be able to recognize them as KVO error messages in the log output.

A couple of approaches you could take:

• store the UI elements in a UIView - in a xib file and instantiate it from your base class and add it as a sub view in the main view, typically self.view. Then you would simply use the storyboard layout with basically blank view controllers holding their place in the storyboard but with the correct view controller sub class assigned to them. Since they would inherit from the base, they would get that view.

• create the layout in code and install it from your base view controller. Obviously this approach defeats the purpose of using the storyboard, but may be the way to go in your case. If you have other parts of the app that would benefit from the storyboard approach, it's ok to deviate here and there if appropriate. In this case, like above, you would just use bank view controllers with your subclass assigned and let the base view controller install the UI.

It would be nice if Apple came up with a way to do what you propose, but the issue of having the graphic elements pre-linked with the controller subclass would still be an issue.

have a great New Year!! be well