hello

Nice Question

first of all you have to import two framework in you group listed below

-AddressBook.framework

-AddressBookUI.framework

and then import two file in .h file

#import <AddressBook/AddressBook.h>
#import <AddressBookUI/AddressBookUI.h>

and then you have to use some method in .m file

- (void)peoplePickerNavigationControllerDidCancel:(ABPeoplePickerNavigationController *)peoplePicker {
    // assigning control back to the main controller
    [self dismissModalViewControllerAnimated:YES];
}

- (BOOL)peoplePickerNavigationController: (ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person {

    // setting the first name
    firstName.text = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty);

    // setting the last name
    lastName.text = (NSString *)ABRecordCopyValue(person, kABPersonLastNameProperty);   

    // setting the number
    /*
     this function will set the first number it finds

     if you do not set a number for a contact it will probably
     crash
     */
    ABMultiValueRef multi = ABRecordCopyValue(person, kABPersonPhoneProperty);
    number.text = (NSString*)ABMultiValueCopyValueAtIndex(multi, 0);

    // remove the controller
    [self dismissModalViewControllerAnimated:YES];

    return NO;
}

- (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier{
    return NO;
}

this is the whole process for implement address book in you application..