How to fetch contacts from AddressBook and store it in array in iOS 6?

How to fetch contacts from AddressBook and store it in array in iOS 6?

I am trying to fetch first name of contact in address book and then to
store it in an array.However i am not able to store the contact in array.
This is what i tried.
-(void)fetchAddressBook
{
ABAddressBookRef UsersAddressBook =
ABAddressBookCreateWithOptions(NULL, NULL);
//contains details for all the contacts
CFArrayRef ContactInfoArray =
ABAddressBookCopyArrayOfAllPeople(UsersAddressBook);
//get the total number of count of the users contact
CFIndex numberofPeople = CFArrayGetCount(ContactInfoArray);
//iterate through each record and add the value in the array
for (int i =0; i<numberofPeople; i++) {
ABRecordRef ref = CFArrayGetValueAtIndex(ContactInfoArray, i);
ABMultiValueRef names = (__bridge ABMultiValueRef)((__bridge
NSString*)ABRecordCopyValue(ref, kABPersonFirstNameProperty));
NSLog(@"name from address book = %@",names); // works fine.
NSString *contactName = (__bridge NSString *)(names);
[self.reterivedNamesMutableArray addObject:contactName];
NSLog(@"array content = %@", [self.reterivedNamesMutableArray
lastObject]);//shows null
}
}