The default app has not been configured yet

Question

I\'m trying to upgrade my app to the new version of Firebase. I went through the setup guide and edited all of my code to match the new syntax. However, when I run the app,

Answer 1

I had several normal working projects with FIRApp.configure () code in AppDelegate.swift:

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        FIRApp.configure()
        return true
    }

Everything worked great for quite some time, but yesterday and today I opened a Swift 3 project inside my Xcode 7.3.1 (I am still working in Swift 2, but opened Swift 3 project to see what is changed), and suddenly in all my Swift 2 apps and projects that I am still working on, got the same error:

The default app has not been configured yet

Every project now when I open in XCode, getting same error, I didn't know what to do, but after implementing @MichaelWilliams' code, everything works fine again.

I have debug my Xcode (clear and reload console), but nothing works beside this new approach by Michael.

This one resolved my problem:

override init() {
   FIRApp.configure()
   FIRDatabase.database().persistenceEnabled = true
}

Can this new code somehow make my app's unstable and can I be afraid to see problems with connecting/working with Firebase database now?