What property should I use for a Dispatch Queue after ARC?

Question

I maintain a dispatch queue as a property with my view controller. I create this queue once in my view controller\'s init method, and reuse a few times for some background t

Answer 1

TL;DR: dispatch_queue_t is an Objective C object now and can be managed with ARC.

I haven't tested how far back this is true, but using the iOS 7 SDK and Xcode 5, dispatch_queue_t is an object type. I am declaring a property for a queue as

@property (nonatomic, strong) dispatch_queue_t syncQueue;

The compiler is happy and everything works as expected. I know definitively that this used to not work in iOS 4 or 5 (pre-ARC it was retain instead of strong). I dug into the definition for dispatch_queue_t and found this:

/*!
 * @typedef dispatch_queue_t
 *
 * @abstract
 * Dispatch queues invoke blocks submitted to them serially in FIFO order. A
 * queue will only invoke one block at a time, but independent queues may each
 * invoke their blocks concurrently with respect to each other.
 *
 * @discussion
 * Dispatch queues are lightweight objects to which blocks may be submitted.
 * The system manages a pool of threads which process dispatch queues and
 * invoke blocks submitted to them.
 *
 * Conceptually a dispatch queue may have its own thread of execution, and
 * interaction between queues is highly asynchronous.
 *
 * Dispatch queues are reference counted via calls to dispatch_retain() and
 * dispatch_release(). Pending blocks submitted to a queue also hold a
 * reference to the queue until they have finished. Once all references to a
 * queue have been released, the queue will be deallocated by the system.
 */
DISPATCH_DECL(dispatch_queue);

By the sounds of that, it shouldn't work, so I checked the definition of DISPATCH_DECL and found this, which explains everything:

/*
 * By default, dispatch objects are declared as Objective-C types when building
 * with an Objective-C compiler. This allows them to participate in ARC, in RR
 * management by the Blocks runtime and in leaks checking by the static
 * analyzer, and enables them to be added to Cocoa collections.
 * See  for details.
 */