Issue with Core Data fetch request

Question

I'm quite new to iOS Development and I'm having some issues with a Core Data fetch request. I'm using Xcode 9-beta and swift 4.

Whenever I update my database, I'm loading the new data with a fetch request, to make some calculations and fill a table view.

My challenge is that every time I do a fetch request for an entity, I'm getting the same data, even though it changed. It seems to me that is reusing the data from a previous fetch request, because if I close the app and open it again, it shows me the new stored data.

Here's my code:

if let context = container?.viewContext {
        context.perform {

            let request: NSFetchRequest<EntityName> = EntityName.fetchRequest()
            let data = try? context.fetch(request)
            self.data = data!

            self.setUI()
        }
}

I'm getting the container from:

let container: NSPersistentContainer? = (UIApplication.shared.delegate as? AppDelegate)?.persistentContainer

I gave some generic names, as I think that's irrelevant for the question.

Any thoughts?

Thanks, JL

Answer 1

I got the viewContext from the container because I needed the UI thread. I guess that was my problem. I solved it passing the context I used to fetch and create the data and dispatching the request to the main queue:

func loadData(with context: NSManagedObjectContext) {

    context.perform {

        DispatchQueue.main.async {
            let request: NSFetchRequest<EntityName> = EntityName.fetchRequest()
            let data = try? context.fetch(request)
            self.data = data!

            self.setUI()
        }
    }
}

I hope it helps.