I'm a big newbie so bare with me please!

I'm working with an example from a book that asks to build a class to work with fractions. I created a class called "Fraction" that is a subclass of "Object".

When I try to allocate memory and initialize an instance of Fraction it gives me an error. The error states "No known class method for selector 'alloc'" (and the same for the "init" method. It sounds like it is not inheriting the methods from the Object class. I perused my interface declaration about a million times and can't find an error that could be causing this.

Is there something about Xcode 4 that could be causing this? I'm pretty much clueless.