Utilize NSFetchedResultsController to update the deck when answers are recorded.

day-086/Projects/Flashzilla/Flashzilla.xcodeproj/project.pbxproj

@@ -34,7 +34,7 @@
 		F378AA0E23D4CC6400296A76 /* DraggableCardView.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA0D23D4CC6400296A76 /* DraggableCardView.swift */; };
 		F378AA1023D5BAD500296A76 /* CardDeckView.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA0F23D5BAD500296A76 /* CardDeckView.swift */; };
 		F378AA1323D63AA700296A76 /* NumberFormatters.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1223D63AA700296A76 /* NumberFormatters.swift */; };
-		F378AA1523D7156200296A76 /* Card+Outcome.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1423D7156100296A76 /* Card+Outcome.swift */; };
+		F378AA1523D7156200296A76 /* Card+AnswerState.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1423D7156100296A76 /* Card+AnswerState.swift */; };
 		F378AA1723D733EF00296A76 /* EditDeckView.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1623D733EE00296A76 /* EditDeckView.swift */; };
 		F378AA1923D7359B00296A76 /* EditDeckView+ViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1823D7359B00296A76 /* EditDeckView+ViewModel.swift */; };
 		F378AA1B23D7A06600296A76 /* CountdownTimerView.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA1A23D7A06500296A76 /* CountdownTimerView.swift */; };
@@ -43,6 +43,7 @@
 		F378AA2323D7B8D900296A76 /* CardDeck+CoreDataProperties.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA2123D7B8D900296A76 /* CardDeck+CoreDataProperties.swift */; };
 		F378AA2523D7B91E00296A76 /* CardDeck+Computeds.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA2423D7B91E00296A76 /* CardDeck+Computeds.swift */; };
 		F378AA3023D8909C00296A76 /* KeyboardAvoider in Frameworks */ = {isa = PBXBuildFile; productRef = F378AA2F23D8909C00296A76 /* KeyboardAvoider */; };
+		F378AA3223D8A6EA00296A76 /* Card+FetchHelpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = F378AA3123D8A6EA00296A76 /* Card+FetchHelpers.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -72,7 +73,7 @@
 		F378AA0D23D4CC6400296A76 /* DraggableCardView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DraggableCardView.swift; sourceTree = "<group>"; };
 		F378AA0F23D5BAD500296A76 /* CardDeckView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CardDeckView.swift; sourceTree = "<group>"; };
 		F378AA1223D63AA700296A76 /* NumberFormatters.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NumberFormatters.swift; sourceTree = "<group>"; };
-		F378AA1423D7156100296A76 /* Card+Outcome.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Card+Outcome.swift"; sourceTree = "<group>"; };
+		F378AA1423D7156100296A76 /* Card+AnswerState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Card+AnswerState.swift"; sourceTree = "<group>"; };
 		F378AA1623D733EE00296A76 /* EditDeckView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EditDeckView.swift; sourceTree = "<group>"; };
 		F378AA1823D7359B00296A76 /* EditDeckView+ViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "EditDeckView+ViewModel.swift"; sourceTree = "<group>"; };
 		F378AA1A23D7A06500296A76 /* CountdownTimerView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CountdownTimerView.swift; sourceTree = "<group>"; };
@@ -80,6 +81,7 @@
 		F378AA2023D7B8D900296A76 /* CardDeck+CoreDataClass.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "CardDeck+CoreDataClass.swift"; sourceTree = "<group>"; };
 		F378AA2123D7B8D900296A76 /* CardDeck+CoreDataProperties.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "CardDeck+CoreDataProperties.swift"; sourceTree = "<group>"; };
 		F378AA2423D7B91E00296A76 /* CardDeck+Computeds.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "CardDeck+Computeds.swift"; sourceTree = "<group>"; };
+		F378AA3123D8A6EA00296A76 /* Card+FetchHelpers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Card+FetchHelpers.swift"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -216,7 +218,8 @@
 			isa = PBXGroup;
 			children = (
 				F378A9F423D44E3800296A76 /* Card+CoreDataClass.swift */,
-				F378AA1423D7156100296A76 /* Card+Outcome.swift */,
+				F378AA3123D8A6EA00296A76 /* Card+FetchHelpers.swift */,
+				F378AA1423D7156100296A76 /* Card+AnswerState.swift */,
 				F378A9F523D44E3900296A76 /* Card+CoreDataProperties.swift */,
 			);
 			path = Card;
@@ -382,6 +385,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				F378AA0423D48D6D00296A76 /* CardDeckContainerView+ViewModel.swift in Sources */,
+				F378AA3223D8A6EA00296A76 /* Card+FetchHelpers.swift in Sources */,
 				F378AA1E23D7A0B900296A76 /* CountdownTimerView+ViewModel.swift in Sources */,
 				F378A9F623D44E3900296A76 /* Card+CoreDataClass.swift in Sources */,
 				F378AA0C23D4A5D300296A76 /* View+Stacked.swift in Sources */,
@@ -400,7 +404,7 @@
 				F378A9E623D43A6900296A76 /* CoreDataManager+Utils.swift in Sources */,
 				F378AA1023D5BAD500296A76 /* CardDeckView.swift in Sources */,
 				F378AA1723D733EF00296A76 /* EditDeckView.swift in Sources */,
-				F378AA1523D7156200296A76 /* Card+Outcome.swift in Sources */,
+				F378AA1523D7156200296A76 /* Card+AnswerState.swift in Sources */,
 				F378AA1923D7359B00296A76 /* EditDeckView+ViewModel.swift in Sources */,
 				F378A9F323D43CAA00296A76 /* PreviewData+Cards.swift in Sources */,
 				F378AA0223D48CB900296A76 /* CardDeckContainerView.swift in Sources */,

day-086/Projects/Flashzilla/Flashzilla/Data/Models/Card Deck/CardDeck+CoreDataClass.swift

@@ -12,7 +12,7 @@ import CoreData
 
 @objc(CardDeck)
 public class CardDeck: NSManagedObject {
-
+    
 }
 
 extension CardDeck: Identifiable {}

day-086/Projects/Flashzilla/Flashzilla/Data/Models/Card Deck/CardDeck+CoreDataProperties.swift

@@ -21,6 +21,7 @@ extension CardDeck {
     @NSManaged public var cards: NSSet?
 }
 
+
 // MARK: Generated accessors for cards
 extension CardDeck {
 

day-086/Projects/Flashzilla/Flashzilla/Data/Models/Card/Card+CoreDataProperties.swift

@@ -12,11 +12,6 @@ import CoreData
 
 
 extension Card {
-
-    @nonobjc public class func fetchRequest() -> NSFetchRequest<Card> {
-        return NSFetchRequest<Card>(entityName: "Card")
-    }
-
     @NSManaged public var prompt: String?
     @NSManaged public var answer: String?
     @NSManaged public var decks: NSSet?

day-086/Projects/Flashzilla/Flashzilla/Data/Models/Card/Card+FetchHelpers.swift

@@ -0,0 +1,51 @@
+//
+//  Card+FetchHelpers.swift
+//  Flashzilla
+//
+//  Created by CypherPoet on 1/22/20.
+// ✌️
+//
+
+import Foundation
+import CoreData
+import CypherPoetCoreDataKit_PredicateUtils
+
+
+extension Card {
+
+    @nonobjc public class func fetchRequest() -> NSFetchRequest<Card> {
+        return NSFetchRequest<Card>(entityName: "Card")
+    }
+    
+    
+    public enum SortDescriptors {
+    }
+    
+    
+    public enum Predicate {
+        
+        public static func cards(in cardDeck: CardDeck) -> NSPredicate {
+            let keyword = NSComparisonPredicate.keyword(for: .contains)
+            
+            let predicate = NSPredicate(
+                format: "%K \(keyword) %@",
+                #keyPath(Card.decks),
+                cardDeck.objectID
+            )
+            
+            return predicate
+        }
+    }
+    
+    
+    @nonobjc public class func fetchRequest(
+        forCardsIn cardDeck: CardDeck
+    ) -> NSFetchRequest<Card> {
+        let fetchRequest: NSFetchRequest<Card> = Self.fetchRequest()
+        
+        fetchRequest.sortDescriptors = []
+        fetchRequest.predicate = Self.Predicate.cards(in: cardDeck)
+        
+        return fetchRequest
+    }
+}

day-086/Projects/Flashzilla/Flashzilla/Reusables/Protocols/FetchedResultsControlling.swift

@@ -16,7 +16,11 @@ public protocol FetchedResultsControlling: NSObject {
     var fetchRequest: NSFetchRequest<FetchedResult> { get }
     var fetchedResultsController: NSFetchedResultsController<FetchedResult> { get }
     
-    func makeFetchedResultsController() -> FetchedResultsController
+    func makeFetchedResultsController(
+        sectionNameKeyPath: String?,
+        cacheName: String?
+    ) -> FetchedResultsController
+    
     func extractResults(from fetchedResultsController: FetchedResultsController) -> [FetchedResult]
 }
 
@@ -26,12 +30,15 @@ extension FetchedResultsControlling {
     public typealias FetchRequest = NSFetchRequest<FetchedResult>
 
     
-    public func makeFetchedResultsController() -> FetchedResultsController {
+    public func makeFetchedResultsController(
+        sectionNameKeyPath: String? = nil,
+        cacheName: String? = nil
+    ) -> FetchedResultsController {
         .init(
             fetchRequest: fetchRequest,
             managedObjectContext: CurrentApp.coreDataManager.mainContext,
-            sectionNameKeyPath: nil,
+            sectionNameKeyPath: sectionNameKeyPath,
-            cacheName: nil
+            cacheName: cacheName
         )
     }
     

day-086/Projects/Flashzilla/Flashzilla/Scenes/Card Deck/CardDeckContainerView+ViewModel.swift

@@ -10,13 +10,20 @@
 import SwiftUI
 import Combine
 import CoreData
+import CypherPoetCoreDataKit
 
 
 extension CardDeckContainerView {
     
-    final class ViewModel: ObservableObject {
+    final class ViewModel: NSObject, ObservableObject, FetchedResultsControlling {
+        typealias FetchedResult = Card
+        
+        lazy var fetchRequest: NSFetchRequest<Card> = Card.fetchRequest(forCardsIn: cardDeck)
+        internal lazy var fetchedResultsController: FetchedResultsController = makeFetchedResultsController()
+
         private var subscriptions = Set<AnyCancellable>()
         
+
         @ObservedObject var cardDeck: CardDeck
 
         var isTimerActive = false
@@ -25,6 +32,7 @@ extension CardDeckContainerView {
         
         // MARK: - Published Outputs
         @Published var cards: [Card] = []
+        @Published var visibleCards: [Card] = []
         @Published var timeRemaining: TimeInterval
         
         
@@ -37,7 +45,11 @@ extension CardDeckContainerView {
             self.roundDuration = roundDuration
             self.timeRemaining = roundDuration
 
+            super.init()
+            
+            self.fetchedResultsController.delegate = self
             setupSubscribers()
+            fetchCards()
         }
     }
 }
@@ -65,22 +77,17 @@ extension CardDeckContainerView.ViewModel {
     }
     
     
-    private var cardsPublisher: Publishers.Share<AnyPublisher<[Card], Never>> {
+    private var visibleCardsPublisher: AnyPublisher<[Card], Never> {
-        cardDeck.publisher(for: \.cards)
+        $cards
-            .map { _ in self.cardDeck.cardsArray }
+            .map { $0.filter { $0.answerState == .unanswered } }
+//            .print("visibleCardsPublisher")
             .eraseToAnyPublisher()
-            .share()
     }
 }
 
 
 // MARK: - Computeds
 extension CardDeckContainerView.ViewModel {
-
-    var visibleCards: [Card] {
-        cards.filter { $0.answerState == .unanswered }
-    }
-
     var isDeckEmpty: Bool { visibleCards.isEmpty }
 }
 
@@ -89,6 +96,12 @@ extension CardDeckContainerView.ViewModel {
 // MARK: - Public Methods
 extension CardDeckContainerView.ViewModel {
     
+    func fetchCards() {
+        try? fetchedResultsController.performFetch()
+        cards = extractResults(from: fetchedResultsController)
+    }
+    
+    
     func resetDeck() {
         cards.forEach { $0.answerState = .unanswered }
         
@@ -100,13 +113,14 @@ extension CardDeckContainerView.ViewModel {
         isTimerActive = false
     }
     
+    
     func resumeRound() {
         isTimerActive = true
     }
     
     
     func record(_ answerState: Card.AnswerState, forCardAt index: Int) {
-        let card = cards[index]
+        let card = visibleCards[index]
         
         guard let managedObjectContext = card.managedObjectContext else { fatalError() }
         
@@ -120,14 +134,13 @@ extension CardDeckContainerView.ViewModel {
 }
 
 
-
 // MARK: - Private Helpers
 private extension CardDeckContainerView.ViewModel {
 
     func setupSubscribers() {
-        cardsPublisher
+        visibleCardsPublisher
             .receive(on: DispatchQueue.main)
-            .assign(to: \.cards, on: self)
+            .assign(to: \.visibleCards, on: self)
             .store(in: &subscriptions)
         
         timeRemainingPublisher
@@ -148,3 +161,15 @@ private extension CardDeckContainerView.ViewModel {
             .store(in: &subscriptions)
     }
 }
+
+
+// MARK: - NSFetchedResultsControllerDelegate
+extension CardDeckContainerView.ViewModel: NSFetchedResultsControllerDelegate {
+    
+    func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
+        guard let controller = controller as? FetchedResultsController else { return }
+        
+        print("controllerDidChangeContent")
+        cards = extractResults(from: controller)
+    }
+}