Add Boost to Xcode

Problem:
I have installed Boost library but Xcode still nags about not finding it.

Solution:
I am writing this based on XCode 4.4.1. It should be similar to other versions.
1. Click on your project on the left side of XCode
2. Click on the tab Build Settings if it is not selected by default
3. Click on All tab if it is not selected by default
4. Under Header Search Paths Click + for both your Debug and Release directories and add Boost directory (for example /usr/local/boost_1_51_0