getAPNSToken always returns null except right after registration

[willlaserlike]

I'm using the RN 46 and react-native-fcm 7.5.1. Everything works for me in terms that I can get the fcmToken and I can send push messages to ios devices withe the fcmToken. But I'm having trouble to get the apns token from this library.

I have code like this
FCM.getFCMToken()
.then((token) => {console.log('token '+token);})
FCM.getAPNSToken()
.then((apnstoken) => {console.log('apnstoken '+apnstoken);})

For the first time app runs and receives user's permissions for notification, the apnstoken is a valid string. Once the app is killed and restarted, it always gives undefined value for apnstoken.

[willlaserlike]

I found out what happened.

1. [FIRMessagein messaging].APNSToken is supposed to be used for setting the apns token, not reading it. So it's always empty except right after Firebase set it when Firebase gets a new apns token from the system call. To trigger this system call, we need to call [application registerForRemoteNotifications].

2. APNSToken is not a NSString. It's a NSData bytes. And it cannot be converted into a string with NSUTF8StringEncoding. We have to convert it into a hex string and then pass back to javascript side.
   Current code (return null even if it has a NSData value)
   resolve([FIRMessaging messaging].APNSToken);
   Working code (return a hex string)
   NSData *apnsTokenData = [FIRMessaging messaging].APNSToken; const char *data = [apnsTokenData bytes]; NSMutableString *token = [NSMutableString string]; for (NSUInteger i = 0; i < [apnsTokenData length]; i++) { [token appendFormat:@"%02.2hhX", data[i]]; } resolve([token copy]);

[evollu]

fixed