Change/update Firebase notification token or instance id forcefully via code?

Question

What should I do that for changing or requesting the token in firebase? the unique token generated by firebase on the basis of device information.

Answer 1

Now i got my answer after facing many troubles for generating new or change token of firebase for push notification.

1) Delete old Firebase token

let instance = FIRInstanceID.instanceID()
_ = FIRInstanceID.delete(instance)
FIRInstanceID.instanceID().delete { (err:Error?) in
    if err != nil{
        print(err.debugDescription);
    } else {
        print("Token Deleted");
    }
}

2) Request new Firebase token

if let token = FIRInstanceID.instanceID().token() {
    print("Token \(token) fetched");
} else {
    print("Unable to fetch token");
}

FIRMessaging.messaging().connect { (error) in
    if (error != nil) {
        print("Error connecting to FCM. \(error.debugDescription)")
    } else {
        print("Connected to FCM.")
    }
}

UPDATE FOR SWIFT 4 & Firebase 4.8.2 (Follow simple two steps)