// Código ioS adicionar userID (Facebook login ou Login Manual)
PFInstallation *currentInstallation = [PFInstallation currentInstallation];
[currentInstallation setObject:userID forKey:@"userID"];
[currentInstallation saveInBackground];

// Código ioS delete userID (logout)
PFInstallation *currentInstallation = [PFInstallation currentInstallation];
[currentInstallation removeObjectForKey:@"userID"];
[currentInstallation saveInBackground];