ABAddressBookGetPersonCount returns -1 in iOS - objective-c

Question

I am running into a situation where ABAddressBookGetPersonCount is returning -1. The tester assures me there contacts do exist in the address book. All the handsets are running iOS 6.0.1.
Here's the code:
NSMutableDictionary *myAddressBook = [[NSMutableDictionary alloc] init];
ABAddressBookRef addressBook = ABAddressBookCreate();
CFArrayRef people = ABAddressBookCopyArrayOfAllPeople(addressBook);
int numEntries = ABAddressBookGetPersonCount(addressBook);
if (numEntries == 0)
{
NSString *title = NSLocalizedString(#"error", nil);
NSString *description = NSLocalizedString(#"error_empty_contacts", nil);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
message:description
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alert show];
return;
}
NSLog(#"emails: found %d", numEntries);
I am not able to reproduce this on any of my handsets, but the tester has tried on 3 handsets. It works properly on an iPhone 5, but not on a 4 or 3;
I can't find any docs that indicate what a value of -1 means. I'm assuming it's an error of some kind, but what?

Answer 1

Under iOS 6, this code isn't valid. You have to verify that your app has permission to access the address book. Most likely, the -1 is an indication that the app has no permission (or an unknown permission state) on those devices.
From the docs for ABAddressBookRequestAccessCompletionHandler:
CFErrorRef myError = NULL;
ABAddressBookRef myAddressBook = ABAddressBookCreateWithOptions(NULL, &myError);
APLViewController * __weak weakSelf = self; // avoid capturing self in the block
ABAddressBookRequestAccessWithCompletion(myAddressBook,
^(bool granted, CFErrorRef error) {
if (granted) {
NSArray *theSmiths = CFBridgingRelease(
ABAddressBookCopyPeopleWithName(myAddressBook,
CFSTR("Smith")
)
);
weakSelf.numberOfSmiths = [theSmiths count];
} else {
// Handle the error
}
});
CFRelease(myAddressBook);
If you need to support iOS 5.x or 4.x you need to properly check for the existence of the new methods.