How to draw NSString vertically on iPhone?

Question

Chinese characters can be view horizontally and vertically. I want to let users have both options. How can this be done in an iPhone views?

e.g.

+-------------------------+         +-------------------------+
| Hello, I am a newbie.   |         |                 b  a  H |
|                         |         |                 i  m  e |
|                         |         |                 e     l |
|                         |   --->  |                 .  a  l |
|                         |         |                       o |
|                         |         |                    n  , |
|                         |         |                    e    |
|                         |         |                    w  I |
+-------------------------+         +-------------------------+