Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>From my experience, this is not necessary as long as both contexts implement either the <code>NSMainQueueConcurrencyType</code> or the <code>NSPrivateQueueConcurrencyType</code>. The important thing to remember is that when interacting with managed object contexts across multiple threads, all messages sent to the context must be sent via either <code>-performBlock:</code> or <code>performBlockAndWait:</code>. </p> <p>In a recent project, I had a parent <code>NSManagedObjectContext</code> that backed an <code>NSFetchedResultsController</code> that was created with the <code>NSMainQueueConcurrencyType</code>. From there I created an <code>NSManagedObjectContext</code> with the <code>NSPrivateQueueConcurrencyType</code> and set the context with the <code>NSMainQueueConcurrencyType</code> as the parent. Now my child context could contain discardable edits when adding a new object that would eventually end up in the table view backed by the <code>NSFetchedResultsController</code> which is backed by the parent context. When I was ready to save my edits and bubble them up to the parent context, the code looked like this.</p> <pre><code>// Save the child context first [childContext performBlock:^{ NSError *error = nil; [childContext save:&amp;error]; // Save the changes on the main context [parentContext performBlock:^{ NSError *parentError = nil; [parentContext save:&amp;parentError]; }]; }]; </code></pre> <p>Now I can't say with certainty that this is the correct way to do this because the documentation on this is pretty sparse at the moment. It might be helpful if you could show some code that you believe is causing deadlocks. If you're in the developer program, you may want to check out the WWDC session videos regarding Core Data from this year. I believe there are two, one for Mac OS X and one for iOS, that basically touch on the same ideas but each contain unique information as well.</p>
    singulars
    1. This table or related slice is empty.
    1. PODoes a Core Data parent ManagedObjectContext need to share a concurrency type with the child context?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USMark Adams
    1. USMark Adams
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTBountyClose
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COAdded details above, no code yet.
      singulars
      1. PO
      1. USStripes
    2. COBest & only answer with an hour left on the clock. I award you 50 points! (and I've watched one of the two WWDC videos, now that I know the other has some unique info I'll give that a watch too).
      singulars
      1. PO
      1. USStripes
    3. COI think the only difference is that Stripes make parent context backing by private queue and child context backing by main queue. Yet @Mark you do the other way around. I think that makes the difference of deadlock or not. Apple seems to support Stripes' way in WWDC 2012 session 214.
      singulars
      1. PO
      1. USPhilip007
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload