Добавил дебаг флаг для отображения ошибок доступа к контексту CoreData из неверной очереди

Example/DAO.xcodeproj/xcshareddata/xcschemes/DAO-Example.xcscheme

@@ -40,7 +40,6 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      language = ""
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
          <TestableReference
@@ -90,7 +89,6 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      language = ""
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"
@@ -107,6 +105,12 @@
             ReferencedContainer = "container:DAO.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
+      <CommandLineArguments>
+         <CommandLineArgument
+            argument = "-com.apple.CoreData.ConcurrencyDebug 1"
+            isEnabled = "YES">
+         </CommandLineArgument>
+      </CommandLineArguments>
       <AdditionalOptions>
       </AdditionalOptions>
    </LaunchAction>