Threads, tasks, and the Objective-C SDK

Robert S.138

Having completed an Android version of my app, I was hoping that the Objective-C version for iOS would be similar.  But looking at the DBRoulette example, there seems to be a ****** difference regarding threading.  Is it correct that all the code shown in the four .m source files runs in the UI thread?  This may be fine for transferring one file at a time, when the only thing the UI thread needs to do is respond when the background operation is done.  But in my app, I need to transfer an entire folder, and recursively, any subfolders.  In Android I did this in an Async Task, where my doInBackground method did all the heavy lifting, handling folder recursion, etc.  The UI thread got periodic postings of progress through the onProgressUpdate method. And the UI thread could cause an early termination of the Async Task the usual way.

In the iOS version, I would like to use the same pattern, doing all the work in a worker thread.  But I don't see how to implement that pattern using the functions shown in the DBRoulette example.  Is there some other example that uses a worker thread to sequence through a tree of files and transfer them one at a time?

 

Stephen C.14

Thanks for reaching out. Are you looking to specify a custom queue on a route-by-route basis?

If you're looking to simply set a custom queue for all API calls, you can do that by supplying a custom `DBTransportClient` with a custom `delegateQueue` when you setup your app. You can read about it more on the GitHub tutorial page here. Do this will mean that all response handler code is executed on a thread other than the main thread.

If you want to specify a queue for reach route, however, the SDK doesn't currently offer that functionality. But we're thinking about implementing it. If you think being able to specify the queue/thread for each API call (in the response handler) would help your workflow a lot, we can try and get the new feature out quickly to you.