Updated sortDescriptor to support localizedCaseInsensitiveCompare:

sortKey: "firstName"
value to observe: "b2"
<n>: section header

- Old code Results - 

<B>
1. Cameroon
<C>
2. Steve
<S>
3. b2

- New Code Results - 

<B>
1. b2
<C>
2. Cameroon
<S>
3. Steve