Integrate Combine Into an App
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Earlier when we defined places we could use Combine in our Jokes app, we determined that fetching a list of saved jokes would be a great piece of functionality to show off the powers of Combine - but we need to have data in the database before we can do that!
import Foundation
import SwiftUI
import CoreData
import ChuckNorrisJokesModel
extension JokeManagedObject {
static func save(joke: Joke, inViewContext viewContext: NSManagedObjectContext) {
guard joke.id != "error" else { return }
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(
entityName: String(describing: JokeManagedObject.self))
fetchRequest.predicate = NSPredicate(format: "id = %@", joke.id)
if let results = try? viewContext.fetch(fetchRequest),
let existing = results.first as? JokeManagedObject {
existing.value = joke.value
existing.categories = joke.categories as NSArray
existing.languageCode = joke.languageCode
existing.translationLanguageCode = joke.translationLanguageCode
existing.translatedValue = joke.translatedValue
} else {
let newJoke = self.init(context: viewContext)
newJoke.id = joke.id
newJoke.value = joke.value
newJoke.categories = joke.categories as NSArray
newJoke.languageCode = joke.languageCode
newJoke.translationLanguageCode = joke.translationLanguageCode
newJoke.translatedValue = joke.translatedValue
}
do {
try viewContext.save()
} catch {
fatalError("\(#file), \(#function), \(error.localizedDescription)")
}
}
}
extension Collection where Element == JokeManagedObject, Index == Int {
// 1
func delete(at indices: IndexSet, inViewContext viewContext: NSManagedObjectContext) {
// 2
indices.forEach { index in
viewContext.delete(self[index])
}
// 3
do {
try viewContext.save()
} catch {
fatalError("\(#file), \(#function), \(error.localizedDescription)")
}
}
}