Core Data: Beyond the Basics

Jul 26 2022 · Swift 5.5, iOS 15, Xcode 13.3.1

Part 1: Fetching & Displaying Launches

04. Filtering Using Predicates

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Previous episode: 03. Sorting Data Using Sort Descriptors Next episode: 05. Dynamically Adjust Sort Descriptors

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You’ve learned quite a bit so far - you know how to save launches to the persistent store, fetch them to display and sort them by properties. But you might have noticed a pretty big flaw in your RocketLaunches app. Build and run the app. Now try tapping on any of the RocketLaunches, mark it as viewed (which sets the isViewed property to true), and then return to the list.

static func unViewedLaunchesFetchRequest() -> FetchRequest<RocketLaunch> {}
let nameSortDescriptor = NSSortDescriptor(key: "name", ascending: true)
let launchDateSortDescriptor = NSSortDescriptor(key: "launchDate", ascending: false)
let isViewedPredicate = NSPredicate
let isViewedPredicate = NSPredicate(format: "%K == %@",)
let isViewedPredicate = NSPredicate(format: "%K == %@", "isViewed", NSNumber(value: false))
return FetchRequest(entity: RocketLaunch.entity(), sortDescriptors: [nameSortDescriptor, launchDateSortDescriptor], predicate: isViewedPredicate)
let launchesFetchRequest = RocketLaunch.unViewedLaunchesFetchRequest()