Remote Push Notification when App is not running crashes

Question

If I send a remote push notification, everything works great in background / foreground. But if I kill my app and want to handle the push notification, the app starts and crashes after a few ms.

Here is my didFinishLaunchingWithOptions function:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        UNUserNotificationCenter.current().requestAuthorization(options:
            [[.alert, .sound, .badge]],
            completionHandler: { (granted, error) in
            // Handle Error
        })
        application.registerForRemoteNotifications()

        if let options: NSDictionary = launchOptions as NSDictionary? {
            let remoteNotification =
                options[UIApplicationLaunchOptionsKey.remoteNotification]

            if let notification = remoteNotification {
                self.application(application, didReceiveRemoteNotification:
                    notification as! [AnyHashable : Any],
                                 fetchCompletionHandler:  { (result) in
                })

            }
        }

        return true
}

And my didReceiveRemoteNotification function

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {

        let tabBar: UITabBarController = self.window?.rootViewController as! UITabBarController
        let navController: UINavigationController = tabBar.viewControllers![1] as! UINavigationController
        let viewController = navController.viewControllers[0] as! CompanyProfileTableViewController
        //let viewController = tabBar.viewControllers![1] as! CompanyProfileTableViewController

        let notification: CKNotification = CKNotification(fromRemoteNotificationDictionary:
                userInfo as! [String : NSObject])

        print("\(notification)")

        if (notification.subscriptionID == "company-changed") {
            let queryNotification =
                notification as! CKQueryNotification
            print("\(queryNotification)")

            let recordID = queryNotification.recordID

            viewController.fetchRecord(recordID!)
        }

    }

I´m dealing with this problem for more than enough hours but can´t find a proper solution. I also checked

Handling Push Notifications when App is NOT running

If I relunch the app, changes caused by the rPN to the Labels were made. As I have to kill the app I'm not able to debug the code in Xcode while a rPN was sent to the killed app.

Here is the function to fetch records and update the labels

//Fetch records from DB
func fetchRecord(_ recordID: CKRecordID) -> Void {
    let privateDatabase = CKContainer.default().privateCloudDatabase
    var recordIDArray: [CKRecordID] = []
    recordIDArray.append(recordID)

    let fetchRecordsWithID = CKFetchRecordsOperation(recordIDs: recordIDArray)
    fetchRecordsWithID.fetchRecordsCompletionBlock = { (records, error) in
        if error != nil {
            print("Error")
        } else {
            DispatchQueue.main.async() {
                self.currentRecord = records?[recordID]

                let data = NSKeyedArchiver.archivedData(withRootObject: self.currentRecord ?? "none")
                UserDefaults.standard.set(data, forKey: "companyRecord")
                UserDefaults.standard.synchronize()

                if let retrivedData = UserDefaults.standard.object(forKey: "companyRecord") {
                    let companyRecord = NSKeyedUnarchiver.unarchiveObject(with: retrivedData as! Data) as! CKRecord
                    self.companyNameLabel.text = companyRecord["companyName"] as? String
                    self.companyStreetLabel.text = companyRecord["companyStreet"] as? String
                    self.companyZipCodeLabel.text = companyRecord["companyZipCode"] as? String
                }

            }
        }
    }
    privateDatabase.add(fetchRecordsWithID)        
}

Trace stack:

Trace Stack

I guess the problem is in the fetch record function.

Error:

; partial apply forwarder for Swift.(_fatalErrorMessage (Swift.StaticString, Swift.StaticString, Swift.StaticString, Swift.UInt, flags : Swift.UInt32) -> Swift.Never).(closure #2)
    0x1003d11e4 <+96>:  nop    
    0x1003d11e8 <+100>: mov    x0, x25
    0x1003d11ec <+104>: mov    x1, x24
    0x1003d11f0 <+108>: mov    x2, x23
    0x1003d11f4 <+112>: mov    x4, x8
    0x1003d11f8 <+116>: bl     0x1002c4b80               ; function signature specialization <preserving fragile attribute, Arg[1] = [Closure Propagated : reabstraction thunk helper from @callee_owned (@unowned Swift.UnsafeBufferPointer<Swift.UInt8>) -> () to @callee_owned (@unowned Swift.UnsafeBufferPointer<Swift.UInt8>) -> (@out ()), Argument Types : [@callee_owned (@unowned Swift.UnsafeBufferPointer<Swift.UInt8>) -> ()]> of generic specialization <preserving fragile attribute, ()> of Swift.StaticString.withUTF8Buffer <A> ((Swift.UnsafeBufferPointer<Swift.UInt8>) -> A) -> A
->  0x1003d11fc <+120>: brk    #0x1

Answer 1

I finally found the solution. The problem was my fetchRecord function. The labels were not initialized when performing the rPN with a "killed" app.

So there are two ways to solve this problem:

1st:

Modify the didReceiveRemoteNotification method:

if (notification.subscriptionID == "company-changed") {
            let queryNotification =
                notification as! CKQueryNotification
            print("\(queryNotification)")

            let recordID = queryNotification.recordID
            tabBar.selectedIndex = 1
            viewController.fetchRecord(recordID!)
}

I add this ->

tabBar.selectedIndex = 1

This will show up the viewController and labels are initialized fine.

The other solution is to put the part were I set the labels with the new values into viewWillAppear or viewDidLoad.