title: Core Data not saving objects persistently
body: <p>I'm new to Core Data and as such am not sure if I'm making a mistake. I've downloaded some data from a REST API and it successfully saves the <code>JSON</code> response to disk. I'm trying to process the data and save it persistently using Core Data. </p>
  
  <pre><code>NSLog(@"inserted objects: %@", [managedObjectContext insertedObjects]);
      [managedObjectContext performBlockAndWait:^{
          NSError *error = nil;
          if (![managedObjectContext save:&amp;error]) {
              NSLog(@"Unable to save context for class %@", className);
          } else {
              NSLog(@"saved all records!");
          }
      }];
  </code></pre>
  
  <p>I've successfully processed the <code>JSON</code> and added it to an <code>NSManagedObjectContext</code>. In the first line, it shows that I've successfully attempted to insert 2 objects.</p>
  
  <pre><code>inserted objects: {(
      &lt;User: 0xa259af0&gt; (entity: User; id: 0xa259b70 &lt;x-coredata:///User/t44BB97D0-C4B4-4BA6-BD25-13CEFDAE665F3&gt; ; data: {
      email = "vishnu@vishnuprem.com";
      experience = "2013-07-20";
      "first_name" = Vishnu;
      id = 2;
      "job_title" = Developer;
      "last_name" = Prem;
      location = "";
      "phone_number" = "+6590091516";
      "profile_pic" = "";
      "thumbnail_profile_pic" = "";
      "user_id" = 2;
  }),
      &lt;User: 0xa25e460&gt; (entity: User; id: 0xa25e4c0 &lt;x-coredata:///User/t44BB97D0-C4B4-4BA6-BD25-13CEFDAE665F2&gt; ; data: {
      email = "sanchitbareja@gmail.com";
      experience = "2013-07-20";
      "first_name" = Sanchit;
      id = 1;
      "job_title" = Developer;
      "last_name" = Bareja;
      location = "";
      "phone_number" = "+15106127328";
      "profile_pic" = "";
      "thumbnail_profile_pic" = "";
      "user_id" = 1;
  })
  )}
  </code></pre>
  
  <p>When I attempted <code>[managedObjectContext save:&amp;error]</code>, it does so successfully and print out "saved all records" as expected. However, when I go to my application <code>.sqlite</code> file and check for added objects, I realize that it hasn't added any objects to the db. </p>
  
  <p>On app relaunch, I print out a list of objects that are already in the database and it confirms that I've none saved yet. </p>
  
  <p>Does anyone know what's going on and why I'm not able to save the data persistently even though it looks like I've successfully created the 'User' objects that needs to be saved in the Core Data model.</p>
  
  <p>EDIT:</p>
  
  <p>here is where I create the <code>NSPersistentStoreCoordinator</code></p>
  
  <pre><code>// Returns the persistent store coordinator for the application.
  // If the coordinator doesn't already exist, it is created and the application's store added to it.
  - (NSPersistentStoreCoordinator *)persistentStoreCoordinator
  {
      if (_persistentStoreCoordinator != nil) {
          return _persistentStoreCoordinator;
      }
  
      NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"RTModel.sqlite"];
  
      NSError *error = nil;
      NSLog(@"Test 1");
      _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
      NSLog(@"Test 2");
  
      if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&amp;error]) {
          /*
           Replace this implementation with code to handle the error appropriately.
  
           abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
  
           Typical reasons for an error here include:
           * The persistent store is not accessible;
           * The schema for the persistent store is incompatible with current managed object model.
           Check the error message to determine what the actual problem was.
  
  
           If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
  
           If you encounter schema incompatibility errors during development, you can reduce their frequency by:
           * Simply deleting the existing store:
           [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]
  
           * Performing automatic lightweight migration by passing the following dictionary as the options parameter:
           [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
  
           Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
  
           */
          NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
          abort();
      }
  
      return _persistentStoreCoordinator;
  }
  </code></pre>
  
  <p>I have 3 contexts. </p>
  
  <ul>
  <li><p><code>masterManagedObjectContext</code></p></li>
  <li><p><code>backgroundManagedObjectContext</code></p></li>
  <li><p><code>newManagedObjectContext</code></p></li>
  </ul>
  
  <p>master is parent of both background and new. When I query the contexts like this:</p>
  
  <pre><code>    NSError *error = nil;
      NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"User"];
      [request setSortDescriptors:[NSArray arrayWithObject:
                                   [NSSortDescriptor sortDescriptorWithKey:@"id" ascending:YES]]];
      [request setReturnsObjectsAsFaults:NO];
      NSArray *testArray = [[[RTCoreDataController sharedInstance] newManagedObjectContext] executeFetchRequest:request error:&amp;error];
  
      for (User *obj in testArray) {
          NSLog(@"obj.id %@", obj.id);
      }
  
      NSLog(@"query records: %@",testArray);
  </code></pre>
  
  <p>master and background both return the correct obj.id in the NSLog as well as gives the output below for @"query records"</p>
  
  <pre><code>   (
      "&lt;User: 0xa3811d0&gt; (entity: User; id: 0xa381230 &lt;x-coredata:///User/t92BCED2D-CD17-49CC-9EBA-DF8F52F06A002&gt; ; data: {\n    email = \"sanchitbareja@gmail.com\";\n    experience = \"2013-07-20\";\n    \"first_name\" = Sanchit;\n    id = 1;\n    \"job_title\" = Developer;\n    \"last_name\" = Bareja;\n    location = \"\";\n    \"phone_number\" = \"+15106127328\";\n    \"profile_pic\" = \"\";\n    \"thumbnail_profile_pic\" = \"\";\n    \"user_id\" = 1;\n})",
      "&lt;User: 0xa382170&gt; (entity: User; id: 0xa3820b0 &lt;x-coredata:///User/t92BCED2D-CD17-49CC-9EBA-DF8F52F06A003&gt; ; data: {\n    email = \"vishnu@vishnuprem.com\";\n    experience = \"2013-07-20\";\n    \"first_name\" = Vishnu;\n    id = 2;\n    \"job_title\" = Developer;\n    \"last_name\" = Prem;\n    location = \"\";\n    \"phone_number\" = \"+6590091516\";\n    \"profile_pic\" = \"\";\n    \"thumbnail_profile_pic\" = \"\";\n    \"user_id\" = 2;\n})"
  )
  </code></pre>
  
  <p>however "new" returns <code>(null)</code> for the obj.id in <code>NSLog</code> and returns the following for <code>@"query records"</code>:</p>
  
  <pre><code>(
      "&lt;User: 0xa2b08a0&gt; (entity: User; id: 0x95aebe0 &lt;x-coredata:///User/tBFCC6C5F-7D2C-4AA0-BA96-B806EE360A762&gt; ; data: &lt;fault&gt;)",
      "&lt;User: 0xa2b0910&gt; (entity: User; id: 0xa4b9780 &lt;x-coredata:///User/tBFCC6C5F-7D2C-4AA0-BA96-B806EE360A763&gt; ; data: &lt;fault&gt;)"
  )
  </code></pre>