Getting an NSArray of a single attribute from an NSArray

Question

I am facing a very regular scenario.

I have an NSArray which has object of a custom type, say Person. The Person class has the attributes: firstName, lastName and ag

Answer 1

NSArray will handle this for you using KVC

NSArray *people ...;
NSArray *firstName = [people valueForKey:@"firstName"];

This will give you an array of the firstName values from each entry in the array