I start learning programming with Objective-C, and do not have much knowledge of C. So, bridge casting in iOS 6 is still somewhat confusing for me.
Here is the scenario:
I have a person ABRecordID stored in CoreData as 'NSNumber' attribute. Later on, I would like to access to that person directly, so I want to use the person's ABRecordID to access the contact info using ABAddressBook. Noticed that ABAddressBookGetPersonWithRecordID
needs ABRecordID, below is how I perform casting in my code...
address_book = ABAddressBookCreate();
ABRecordID rec_id = (__bridge ABRecordID)person.record_id;
However, This was not successful and I was given incompatible types casting 'int' into 'ABRecordID' (aka 'int') with a __bridge cast
.
Already confused as it is, what would be a proper way to bridge cast between ARC type and CF type?
Also, in which case should I use (__bridge retained)
instead of (__bridge)
?
The ABRecordID
is a synonym (typedef) for int32_t
which is a 32-bit integer. So typecasting is not the proper approach. You want to create an NSNumber
with the value of the id.
ABRecordId rec_id = person.record_id;
NSNumber *wrapper = [NSNumber numberWithInt:(int)rec_id];
and later:
NSNumber *wrapper = ...
ABRecordId rec_id = (ABRecordId)[wrapper intValue];
Please note that bridging and ARC are irrelevant when going to/from ABRecordId and NSNumber. There is no use of any of the CF
types in this case. You'll know when you are using CF
types because you'll have a variable whose type begins with CF
(such as CFArrayRef
).