Question

Assuming there are still outstanding strong references, does this result in a leak because nobody (neither ARC nor I) is managing the object anymore?

 CFTypeRef cf_object = CFBridgingRetain(arc_object);
 // do stuff
 CFRelease(cf_object);

Answer 1

To answer your question, the above code looks fine. You need to do a CFRelease when you are doing a CF Create, Retain or Copy. As Rob suggested you can also look into the usage of CFBridgingRelease. For more details related to the ARC changes, you can look into this Raywenderlich tutorial.

As per apple documentation of CFBridgingRetain,

Casts an Objective-C pointer to a Core Foundation pointer and also
transfers ownership to the caller.

CFTypeRef CFBridgingRetain(id X)

Discussion:
You use this function to cast an Objective-C object as Core
Foundation-style object and take ownership of the object so that you
can manage its lifetime. You are responsible for subsequently
releasing the object.

Here you need to release the cf_object which ARC wont take care of it. Once you call CFRelease, it will be released.

Documentation on CFBridgingRelease

Moves a non-Objective-C pointer to Objective-C and also transfers
ownership to ARC.

id CFBridgingRelease(CFTypeRef X)

Discussion: You use this function to cast a Core Foundation-style object as an Objective-C object and transfer ownership of the object
to ARC such that you don’t have to release the object.

Note that when you use CFBridgingRelease, it will transfer the ownership to ARC and ARC will manage it.

For eg:-

CFStringRef cfName = ABRecordCopyValue(person, kABPersonFirstNameProperty);
NSString *name = (NSString *)CFBridgingRelease(cfName);

ARC will manage name here.