Fix compilation errors using isEqual instead of ==

I was having some compilation errors which I was able to fix using `isEqual` instead of `==` at some places.

![Screen Shot 2013-03-22 at 10 25 47 AM](https://f.cloud.github.com/assets/107672/290963/2d35121c-92f8-11e2-9089-6bea39864011.png)

Btw, since I'm not an obj-c programmer, I don't know if I did something wrong (but it fixed my issue).