CoreDataResults

This one is a bit of an experiment for creating a useful CoreData API that abstracts all the boilerplate for fetching. Most I've seen start from the entity and require the managed object context as an argument.

This one starts with the managed object context as the focus of making queries. You add extensions for your managed object subclasses, in this case Page and Topic:

extension NSManagedObjectContext {
    var pages: Entity<Page> {
        return entity()
    }

    var topics: Entity<Topic> {
        return entity()
    }
}

Then, if you use viewContext from NSManagedContainer you can call:

viewContext.pages.sorted(with: [NSSortDescriptor(key: "title", ascending: true)]).managedObjects

viewContext.pages.sorted(with: [NSSortDescriptor(key: "title", ascending: true)]) sets up the fetch request parameters, and then calling .managedObjects is when the fetch is actually made. Alternatively you can call .managedObjectIDs, .count, .dictionaries, even .first.

There are some shortcuts like:

viewContext.pages.all that will return all pages as [Page], and viewContext.pages.count that will return an integer.

You can stack all the api calls for finer control over querying:

viewContext.pages.matching(predicate: NSPredicate(format: "%K == %@", "topic", "General"))
                 .sorted(with: [NSSortDescriptor(key: "created", ascending: true)])
                 .limit(to: 10)
                 .managedObjects

It's not really complete yet, just trying it out to see where it goes, and if the API feels natural. There's an early attempt at supporting sync queries as well.