How to share (MVC) model between controllers in Swift / XCode?

Question

I am currently creating my first Swift / Mac application and I have the problem of sharing a model (in the MVC sense) between several controllers.

In C# for example one would first create a model, then a number of view models, and then plug that model into them like this:

var gameEngine = new MyGameEngine()
var vm1 = new ViewModelCockpit(gameEngine);
var vm2 = new ViewModelOptionsDialog(gameEngine);

However, in XCode it seems that my controllers I am supposed to place into the .xib, which are, in turn, automatically instantiated.

What is given Swift's language features and XCode / Objective-C existing standards the best and most professional way have a number of heavyweight models that can be shared and accessed from several controllers? (Heavyweight in the sense that they take some time, memory or complex logic / dependencies) to load and might not easily be put into the .xib themselves.

Potential answers could be: global variables, some magic / static properties, ... Ideally the solution should feel solid in a software engineering sense and take Swift's language features into account.

Where did you get "new" from? Also, download the WWDC app and take look at the videos. This is how we are all learning at the moment. — Fogmeister, Jun 05 '14 at 08:07
The new X() above is how you would do it in C#. I am looking for an equivalent solution to the general problem in XCode / IB / Swift. — left4bread, Jun 05 '14 at 08:10

score 0 · Accepted Answer · edited May 23 '17 at 10:32

0

Depending on how complex your data model is, here are some things to consider:

For complex data models, consider using Core Data
Create a singleton DataController class that gives you access to your models from any controller in your app. In Swift it could be done like this: Using a dispatch_once singleton model in Swift

You only use XIBs/Storyboards for the UI, never for your models.

edited May 23 '17 at 10:32

Community

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answered Jun 05 '14 at 13:29

Johannes Fahrenkrug

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score -1 · Answer 2 · answered Jul 13 '14 at 06:55

I like to create the model(s) first, then pass them into each view's initialiser code, very similar to what you describe in C#. It's also similar to how you would do this in JavaScript (for example, in Backbone JS).

let gameEngine = MyGameEngine()


let vm1 = ViewModelCockpit(nibName: "ViewModelCockpit", bundle: NSBundle.mainBundle(), gameEngine: gameEngine)
let vm2 = ViewModelOptionsDialog(nibName: "ViewModelOptionsDialog", bundle: NSBundle.mainBundle(), gameEngine: gameEngine)

class ViewModelCockpit: NSViewController {
  var myGameEngineModel: GameEngineModel

  init(nibName nibNameOrNil: String!, bundle nibBundleOrNil: NSBundle!, myGameEngineModel: GameEngineModel) {
    self.myGameEngineModel = myGameEngineModel

    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
  }
}

Note — you have to call the super.init() of the parent class, and if you forget, Xcode very nicely reminds you! I use Xcode's autocompletion to provide me with the usual init function and its exact args.

How to share (MVC) model between controllers in Swift / XCode?

2 Answers2