Solution 1:

You can get the push token for OneSignal SDK like this:

 OneSignal.promptForPushNotifications(userResponse: { accepted in
  print("User accepted notifications: \(accepted)")
            
  if let deviceState = OneSignal.getDeviceState() {
    let userId = deviceState.userId
    let pushToken = deviceState.pushToken
    let subscribed = deviceState.isSubscribed
    print("pushToken ====> \(pushToken)") //Here you can get the token
  }
 })

Keep coding........... :)

Solution 2:

OneSignal API states IdsAvailable is the method you would use:

[OneSignal IdsAvailable:^(NSString* userId, NSString* pushToken) {
    NSLog(@"UserId:%@", userId);
    if (pushToken != nil)
        NSLog(@"pushToken:%@", pushToken);
}];

Is the method to get the token; mentioned here.