subscribing and unsubcribing to/from many topics dynamically?

[thomasdola]

first of all thanks for this awesome library.
from what i got from your readme => i can only call GMCManager.getInstance(this).subscribeTopic("Gospel"); from onDeviceRegisted.
but i have a case where the user can follow and unfollow many music genres withing a single activity.
=>when the user click follow -> say: Gospel, HipHop
=> i have to call GCMManager.getInstance(this).subscribeTopic("Gospel"); and the same function for
for the HipHop Genre.
=>Same process applies to unfollowing the generes.
So how can i do that? And how will i know onDeviceRegistered() has been called?