How to force SUP to synchronize mbo
===

I am trying to synchronize the mbo in my ios application. Unwired Platform wrap BAPI function to MBO. 
1 What should I do to update the MBO? 
I tried to use the synchronize method. It did not helps. Only the consistent use of methods Subscribe and unsubscribe helps to force update the object. I sync via the personalization parameters. 
2 Can I get a few objects in a single synchronization?