How to handle timeout in queries with Firebase

Question

I noticed that if I execute a query in Firebase and the database server is not reachable, the callback waits just forever (or until the server is reachable again).

W

Answer 1

Here's my solution for the Firebase iOS SDK, this may be helpful for others:

extension DatabaseReference {

    func observe(_ eventType: DataEventType, timeout: TimeInterval, with block: @escaping (DataSnapshot?) -> Void) -> UInt {

        var handle: UInt!

        let timer = Timer.scheduledTimer(withTimeInterval: timeout, repeats: false) { (_) in
            self.removeObserver(withHandle: handle)
            block(nil)
        }

        handle = observe(eventType) { (snapshot) in
            timer.invalidate()
            block(snapshot)
        }

        return handle
    }

}

Usage:

database.child("users").observe(.value, timeout: 30) { (snapshot) in

    guard let snapshot = snapshot else {
        // Timeout!
        return
    }

    // We got data within the timeout, so do something with snapshot.value
}