Minor Fixes and Updates to Latest Xcode & SDK

Howdy howdy,

As someone just getting into Mac development recently, I just wanted to let you know how much I appreciate your blog and this library and the insight and help they provided for me.

I have a few changes here that fix a single compilation error and a few warnings. It's a small set of changes, but I was hoping to have these included so that I could more easily incorporate this code into my project.

Cheers,
Mattt