Hi,
Yes, the documentation is wrong or confusing at best, I’ve tried it, it doesn’t
work. I think it’s meant for a number of operations that need to wait for the
preceding operation to complete before the next one continues.
I also wondered if the NSOperation “waitUntilFinished” method might work, but
it doesn’t seem to either. I’m about to revisit this, I did the testing a while
back but had to leave it to get something else done. I’ve got a few more things
I need to do this morning and then I’ll be at a point where I can investigate
again.
About your dispatch semaphore suggestion, do you mean use it instead of an
NSOperation or as well as?
Thanks a lot
Dave
On 3 Jun 2014, at 22:54, Jeffrey Robert Kelley <slauncha...@gmail.com> wrote:
> That’s not what the documentation says:
>
>> If YES, the current thread is blocked until all of the specified operations
>> finish executing. If NO, the operations are added to the queue and control
>> returns immediately to the caller.
>
>
> So, if you’re experiencing different behavior, I would say that’s a bug that
> should be filed.
>
> That doesn’t solve your question, though. Have you tried using dispatch
> semaphores? They’re a pretty easy way to synchronize tasks:
>
>> dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
>>
>> [self performLongRunningAsynchronousTaskWithCompletionHandler:^{
>> dispatch_semaphore_signal(semaphore);
>> }];
>>
>> dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
>
>
> dispatch_semaphore_wait() will block until the semaphore is signaled at the
> end of the block.
>
>
> Jeff Kelley
>
> slauncha...@gmail.com | @SlaunchaMan | jeffkelley.org
>
> On Jun 3, 2014, at 12:17 PM, Dave <d...@looktowindward.com> wrote:
>
>> I’ve tried that, addOperations:waitUntilFinished: waits for operations
>> currently queued to finish before adding the current operation, it doesn’t
>> Add it to the queue and then wait for it to complete which is what I want.
>>
>> Thanks
>> Dave
>>
>> On 3 Jun 2014, at 19:26, Jeffrey Robert Kelley <slauncha...@gmail.com> wrote:
>>
>>> I think you’re looking for NSOperationQueue’s
>>> -addOperations:waitUntilFinished: method. Should do what you want.
>>>
>>>
>>> Jeff Kelley
>>>
>>> slauncha...@gmail.com | @SlaunchaMan | jeffkelley.org
>>>
>>> On Jun 3, 2014, at 5:51 AM, Dave <d...@looktowindward.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> I think this has been covered before, but all the searches I’ve done don’t
>>>> really cover what I’d like to do.
>>>>
>>>> I have an API that has two modes of operation, Sync and Async.
>>>>
>>>> In Sync mode calls to the API MUST be on a background thread and the data
>>>> is returned to the caller with a possibility that the thread is blocked
>>>> until the operation has completed.
>>>>
>>>> In Async mode calls to the API may be on the background thread or the Main
>>>> Thread, a delegate is passed to the API method which returns immediately
>>>> and the Delegate is called when the operation completes or fails.
>>>>
>>>> This all works, however I have some existing code that I’d like to have
>>>> the same API and be called by a “Manager Class” which calls the correct
>>>> underlying API depending on the context, e.g.
>>>>
>>>> AppLayer—>ManagerClass—>API_A
>>>> —>API_B
>>>>
>>>> API_A is the existing API supporting the Sync/Async interface.
>>>> API_B is the one I wish to create.
>>>>
>>>> The problem is that the existing code uses NSOperationQueue/NSOperation
>>>> accomplish it’s task, this works fine in Async mode, it was easy enough to
>>>> adapt to call the Delegate methods, but I’m not sure how to implement Sync
>>>> mode?
>>>>
>>>> Basically I want to add the NSOperation to the queue and then wait for it
>>>> to complete before returning with the results.
>>>>
>>>> Any ideas suggestions would be greatly appreciated as there seem to be a
>>>> lot of conflicting advice out there on how to do this and I’ve not been
>>>> able to find anything worked as described above.
>>>>
>>>> Thanks a lot.
>>>>
>>>> All the Best
>>>> Dave
>>>>
>>>>
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