Firebase database connected? Swift class

FIRConnection.swift

var connectedRef: FIRDatabaseReference! {
    return FIRDatabase.database().reference().child(".info/connected")
}

class FIRConnection {
    
    static let sharedInstance = FIRConnection()
    
    var handle: UInt?
    var isConnected = false
    
    class func startMonitoring() {
        sharedInstance.handle = connectedRef.observe(.value, with: { (snapshot) in
            guard let connected = snapshot.value as? Bool else {
                print("FIRConnection: Error occurred")
                return
            }
            
            if connected {
                print("FIRConnection: Connected")
                sharedInstance.isConnected = true
            } else {
                print("FIRConnection: Not connected")
                sharedInstance.isConnected = false
            }
        })
    }
    
    class func stopMonitoring() {
        if let handle = sharedInstance.handle {
            connectedRef.removeObserver(withHandle: handle)
        }
    }
    
    class func connected() -> Bool {
        return sharedInstance.isConnected
    }
}