Retrieve data from new Firebase

问题:

Please help. After migrating to new Firebase I can't retrieve data. Use this construction:

let ref = FIRDatabase.database().reference()

override func viewDidLoad() {
    super.viewDidLoad()
    ref.observeEventType(FIRDataEventType.Value, withBlock: { (snapshot) in
        let postDict = snapshot.value as! [String : AnyObject]
        print("\(postDict)")
    })
}

After running I see error:

2016-05-19 10:04:22.264 123a[88652:13688922] The default app has not been configured yet.
2016-05-19 10:04:22.276 123a[88652:13688922] *** Terminating app due to uncaught exception 'MissingDatabaseURL', reason: 'Failed to get FIRDatabase instance: FIRApp object has no databaseURL in its FirebaseOptions object.'
*** First throw call stack:

I read documentation, but can't resolve this problem. GoogleService-Info.plist I add to project.

回答1:

I didn't see this answer yet, I had to add the configure call to the AppDelegate init method. So it looks like:

override init() {
    super.init()
    // Firebase Init
    FIRApp.configure()
}

回答2:

Had the same problem. I looked for linking problems that are related to the plist but that wasn't the problem. I thought maybe it has caused because of that my initial view controller is revoked before the configurations are completed. I solved the problem by experimenting a bit.

My initial view controller was this:

    let ref = FIRDatabase.database().reference()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

}

I've changed that to this:

    var ref = FIRDatabaseReference.init()

override func viewDidLoad() {
    super.viewDidLoad()
    ref = FIRDatabase.database().reference()

    // Do any additional setup after loading the view, typically from a nib.

}

Crash resolved.

回答3:

So, with mine, I also had a ref being declared immediately when the view controller was instantiated. I had to make it load after the app had been configured in the app delegate with FIRApp.configure().

Before:

let serverRef = Firebase("firebaseURL")

After:

lazy var serverRef = FIRDatabase.database().reference()

This delays the instantiation of the database reference until its needed, which wont be until viewDidLoad on your initial view controller.

回答4:

To build on the answer given by @ColdLogic, the reason I had this error was because I had my Firebase database reference being created in an init method on a view controller, not in the viewDidLoad method. Since the init methods for all classes that are instantiated when the app launches are called before the application:DidFinishLaunchingWithOptions method in the AppDelegate, it was causing this crash. Moving this line of code:

class MyViewController {

   var firebaseRef: FIRDatabaseReference

   required init?(coder aDecoder: NSCoder) {
      ...
      firebaseRef = FIRDatabase.database().reference()
   }

   override func viewDidLoad() {
      ...
   }
}

to here:

class MyViewController {

   var firebaseRef: FIRDatabaseReference

   required init?(coder aDecoder: NSCoder) {
      ...
   }

   override func viewDidLoad() {
      ...
      self.firebaseRef = FIRDatabase.database().reference()
   }
}

solved the problem for me.

回答5:

I too had a problem with the Firebase Database. Fixed it by adding

import FirebaseDatabase

to my code

回答6:

Had the same problem today, you need the "firebase_url": "https://xxxxxxxxxx.firebaseio.com" at google-services.json and for that do this steps https://support.google.com/firebase/answer/7015592#android If you had one file from google cloud platform before, maybe there are some differences and you have to check. For me this works.

回答7:

In my case I had to change the configure to be called before calling the super applicationDidLaunch:

[FIRApp configure];

[super application:application didFinishLaunchingWithOptions:launchOptions];

回答8:

I was getting this error until I made FIRApp.configure() the first line in the AppDelegate didFinishLaunchingWithOptions

回答9:

Make sure you have downloaded the GoogleService-Info.plist file from your Firebase console and added to the root of your project directory.

Once you have added it call this function from didFinishLaunchingWithOptions in AppDelegate:

FIRApp.configure()

Thats it, it should be up and running!