OCDiscount is a simple Markdown Cocoa framework which wraps around the discount markdown parser.
$ pod install
$ cd discount
$ wget http://www.pell.portland.or.us/~orc/Code/discount/discount-2.1.7.tar.bz2
$ tar -xf discount-2.1.7
Then, open the OCDiscount.xcworkspace and build the OCDiscount scheme in Xcode.
For more details, go to Wiki.