Question

I’ve the following problem:

I’ve an app with a UITableView as root view. In this tableView are different entries and for each entry (which can be created by the user) I also add a persistentstore to my app.

So, when I start the app from scratch (no saved data etc.) and add an entry, the persistentStore is also created and when I click on the tableViewCell, I can save Data in this generated persistentStore. This works fine if I’m creating an entry and also watch the entry during one single run.

BUT

If I close the app and start again, click on the same entry, I get the following error message:

NSFetchRequest *allUsers = [[NSFetchRequest alloc] init];
[allUsers setAffectedStores:[NSArray arrayWithObject:[[self.tableViewContext persistentStoreCoordinator] persistentStoreForURL:storeURL]]];

* Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘* -[NSArray initWithObjects:count:]: attempt to insert nil object at objects[0]’

So it seems that I want to add a store which is actually nil, because (I guess so) the system can not find any store under this given storeURL (which is the same as the one where I created a store in the first run).

So I guess the persistentStore isn’t there in the second run, so it isn’t saved properly in the first run where it was created.

So how can I save a persistentStore, after I’ve added it, to the persistentStoreCoordinator?

Update:

I think I’ve identified the main problem. The persistentStoreCoordinator has changed after the first run. So how do I save all these things (managedObjectContext, persistentStoreCoordinator) before closing the app?

Can somebody help me?

Update 2

Here is how I create the store:

    NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentPath = [searchPaths objectAtIndex:0];
    NSString* storeFileName = [NSString stringWithFormat:@"%@",newItem.name];
    NSURL *storeURL = [NSURL fileURLWithPath:[documentPath stringByAppendingPathComponent:storeFileName]];                            
     NSError* saveToStoreError;
    if(![[self.addContext persistentStoreCoordinator] addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&saveToStoreError]){
     NSLog(@"Error: %@, %@", saveToStoreError, [saveToStoreError userInfo]);
     abort();
    }
    else
    {
      NSError *saveStoreError;
      if(![self.addContext save:&saveStoreError])
      {
           NSLog(@"Saving Data wasn't possible!");
      }
    }

Update 3
So, after a lot of testing here are my results:

• Creation of the stores works fine. I can create multiple stores and I can access and populate them as long as I’m in a single run of my app.

So something is changing with a restart of my app. I think the error must be associated with the managedObjectContext, the persistentStoreCoordinator or the SAVING of the stores.

Should I change any settings in my app delegate for setting up the managedObjectContext or the persistentStoreCoordinator?

Thanks!

Answer 1

It was simply easy.

I didn’t set addPersistentStoreWithType after restart in a view where I tried to fetch data from this store.

Sorry for this post. Simply easy 😉 bangingmyheadonthewall