How to set property in app delegate for tabview controller - swift

Question

I've read several of the suggested posts that were to help with this problem but could not find something for this particular issue.
I need to set a property on my controller, the book is saying to do so in the app delegate. In the previous assignment using a navbar, this worked:
func application(_ application: UIApplication, didFinishLaunchingWithOptions
launchOptions: [UIApplicationLaunchOptionsKey : Any]?) -> Bool {
// Override point for customization after application launch.
// Create an ItemStore to hold list of items
let itemStore = ItemStore()
// Access the ItemsViewController and set its item store
let itemsController = window!.rootViewController as! ItemsViewController
itemsController.itemStore = itemStore
return true
}
However, creating a similar program I need to use tab bar but can't get it to work and keep running into the error stated above, on the let editcontroller = tabcontroller. - line
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
// Create an pindatabase
let pinDataBase = PinDatabase()
// Access the pairsViewController and set its database
let tabController = window!.rootViewController as! UITabBarController
// this edit controller line is where I am stuck
let editController = tabController.tabBar as! EditViewController
editController.pinDataBase = pinDataBase
return true
}
The error is:
fatal error: unexpectedly found nil while unwrapping an Optional value
The controller I'm trying to set the property on is not the root controller but the third tab if that helps.

Answer 1

Your issue is your attempt to cast the UITabBar to your EditViewController. You need to access the array of view controllers from the tab bar controller and access the one that is actually the EditViewController.
let editController = tabController.viewControllers[2] as! EditViewController
This will access the 3rd view controller and cast it as needed.