Replace core data model whilst in development without migrating the data (OSX xcode 8.1 on El Capitan)

Question

I'm quite new to OSX and xCode development so any help here appreciated. I'm developing an OSX app that stores data in core data and I want to clear the core data model so that it gets re-generated without having to do a migration as I've not pushed the app to any devices yet. I'm incrementally playing around and adding entities as well as changing attributes/etc on existing entities.

I get this error when running the app via xcode after I've added an attribute to an already created entity:

The managed object model version used to open the persistent store is incompatible with the one that was used to create the persistent store.

I've looked at these questions and answers and I'm not getting them to work:

Deleting CoreData store on OS X?

How do I overcome XCode object model version error?

The answer that seems most likely to resolve this (which doesn't work for me) is to go to ~/Library/Developer/Xcode/DerivedData and delete the application folder there. The DerivedData folder does hold a folder with the name of my application and it does get re-generated when I delete it and have the project open in xCode. In fact I've removed all folders in that DerivedData folder but still the same issue.

Anyone knows how to solve this on OSX xcode 8.1 running El Capitan? My App's deployment target is macOS 10.11.

Answer 1

Based on comments etc, I'm sharing two ways I've found that solves this issue for me.

Option 1 - adding app sandbox capability.

Add the capability of 'app sandbox' to your app. The data store then gets moved to the ~/Library/Containers/<appName>. When you want to regenerate the core data store to get around versioning issues, you can then delete that folder.

Option 2 - find out the core data persistent store location via code and then delete those files.

As per Tom Harrington: My app used an NSPersistentStoreCoordinator as U could see in my AppDelegate's core data setup. I got the urls of the persistent stores via this in the AppDelegate.swift (I added this just before where the crash happens when the core data versioning error occurs):

for store in (coordinator?.persistentStores)! 
    print("store url: \(store.url)")
}

This showed that the location of the persistent story for my app was ~/Library/Application Support/com.apple.toolsQA.CocoaApp_CD/TableViewPlayGround.st‌​oredata. FYI: My app bundle id is co.uk.gamba.TableViewPlayGround so this means the data store is not kept in folders relating to my app's bundle when running via xcode. The core data model got replaced without error each time I deleted that file and restarted the app in xcode.

Answer 2

Assuming this is not a document-based app, the Core Data persistent store file will be located in ~/Library/Containers/[your bundle ID]/Data/Documents/. You can remove the full container or specific files. For a document-based app, of course, it'd be in the document.

On iOS you'd just delete the app, but on OS X it's a little different.