How to reference controllers in Swift (MVC) - macos

Question

I have a single window application. Currently I have one xib file (MainMenu.xib) and I have one .swift file (AppDelegate).
If I want to add controls to the UI and assign specific controllers to some of those UI components to to handle additional functionality in a separate file e.g. a NSTextView with a TextViewController - how would I obtain a reference to TextViewController, from within my AppDelegate?
Most tutorials stop short from this and assume that everybody will want to use #IBOutlets to access a controls' properties from the AppDelegate.
I know you can use segues (prepareForSegue) - but my application does not make use of storyboards, and I would like to understand the MVC implementation within cocoa a little better.

Answer 1

Any object can can have its own controller. The AppDelegate is not a holy grail, its just an object which implements methods in the UIApplicationDelegate protocol. Its not a universal switchboard for everything you might wish to connect.
Some of the tutorials do a starting Cocoa dev great disservice by using the AppDelegate as a quick and nasty place to put things. For a storyboard app this all that needs to be contained in the class which conforms to NSApplicationDelegate
import Cocoa
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
}
i.e nothing.
A nominal pattern is one screen has one controller but even that isn't true when you use embedding patterns to control subviews within one window. However consider the simple Cocoa Application project template
The ViewController class is a subclass of NSViewController and is where you might be placing the IBOutlet to your NSTextView and some of the logic to do with interacting with it in that context.
import Cocoa
class ViewController: NSViewController,NSTextDelegate {
#IBOutlet var textView: NSTextView!
override func viewDidLoad() {
super.viewDidLoad()
configureTextController()
}
var textController:TextFieldInteractionManager!
func configureTextController() {
//textcontroller can be local var , alternatively inject it into this VC
textController = TextFieldInteractionManager(textView)
}
}
If you have specific interactions that you want to do across the entire project you might want to place these in another class say TextFieldInteractionManager and make that the delegate of the text field. You would pass the text field to the manager class when you construct the view controller.
The hypothetical TextFieldInteractionManager might be created locally or injected in during the setup of the ViewController instance i.e prepareForSegue(segue: NSStoryboardSegue, sender sender: AnyObject?). The possibilities are varied and will depend on the scope of your app and how you wish to manage your references.
My commonly used pattern is to have a Root view controller which passes references down the to the next controller in the chain. YMMV
Dependancy Injection is a good pattern to know about.
Massive View Controller is a good anti-pattern to know about and avoid.
This is what I meant when i said go and get some domain knowledge. Its an expanding tree of stuff to learn about and why your question as its stands is not a good fit for SO.