FCMToken always null in real device - ios

Question

I am trying to integrate Fireabase notification in iOS for 5 days.
But I can't get the fcmtoken in real device.
It always null.
Here is my code. This code is just from the firebase GitHub sample code.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[FIRApp configure];
[FIRMessaging messaging].shouldEstablishDirectChannel = true;
[FIRMessaging messaging].delegate = self;
// Register for remote notifications. This shows a permission dialog on first run, to
// show the dialog at a more appropriate time move this registration accordingly.
if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_7_1) {
// iOS 7.1 or earlier. Disable the deprecation warnings.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
UIRemoteNotificationType allNotificationTypes =
(UIRemoteNotificationTypeSound |
UIRemoteNotificationTypeAlert |
UIRemoteNotificationTypeBadge);
[application registerForRemoteNotificationTypes:allNotificationTypes];
#pragma clang diagnostic pop
} else {
// iOS 8 or later
// [START register_for_notifications]
if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_9_x_Max) {
UIUserNotificationType allNotificationTypes =
(UIUserNotificationTypeSound | UIUserNotificationTypeAlert | UIUserNotificationTypeBadge);
UIUserNotificationSettings *settings =
[UIUserNotificationSettings settingsForTypes:allNotificationTypes categories:nil];
[[UIApplication sharedApplication] registerUserNotificationSettings:settings];
} else {
// iOS 10 or later
#if defined(__IPHONE_10_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0
// For iOS 10 display notification (sent via APNS)
[UNUserNotificationCenter currentNotificationCenter].delegate = self;
//[FIRMessaging messaging].delegate = self;
UNAuthorizationOptions authOptions =
UNAuthorizationOptionAlert
| UNAuthorizationOptionSound
| UNAuthorizationOptionBadge;
[[UNUserNotificationCenter currentNotificationCenter] requestAuthorizationWithOptions:authOptions completionHandler:^(BOOL granted, NSError * _Nullable error) {
}];
#endif
}
[[UIApplication sharedApplication] registerForRemoteNotifications];
// [END register_for_notifications]
}
return YES; }
Adn I know I can get the femtoken on the didRefreshRegistrationToken delegate method.
The method is fired well on the simulator, but never fired on real device.
And after [FIRApp configure], I tried to get the fcmtoken with this method [[FIRInstanceID instanceID] token],but still token is null.
I have done googling as much as I can do, but get the proper answer on the google.
Please help me.
Any help would be appreciate for me