Swift - Dependency injection in unit test

Question

This the first time am working with dependency injection in swift an this is how I do it , I have a dataManager that is initialized in appDelegate then passed to my first view controller witch will then be passed to other view controllers every time they get pushed to screen :

  if let navigationCtrl = window?.rootViewController as? UINavigationController {

        if let firstViewController = navigationCtrl.topViewController as? FirstViewController {
            firstViewController.dataManager = dataManager
        }
    }

Now doing this, everything works great, but when I go to test each view controller, I always get dataManger to be nil, and I know it's because of the condition I gave in the first place. So is there way to make sure the topViewController always has dataManager variable without inheriting from another ViewController.Thank you

Answer 1

One of these is happening:

• window is nil
• window?.rootViewController is not a UINavigationController
• navigationCtrl.topViewController is not a FirstViewController
• firstViewController.dataManager is nil

It should be a simple debug. Either put some breakpoints and/or print statements to know where the problem is.

Tip(s):

• Make sure to set the view controller's class correctly in XCode/Interface-Builder.