Refactors SaveState.isPreview attribute to Game.previewSaveState relationship

Common/Database/Model/Game.swift

@@ -25,6 +25,7 @@ extension Game
         case typeIdentifier
         
         case gameCollections
+        case previewSaveState
     }
 }
 
@@ -38,6 +39,7 @@ class Game: NSManagedObject, GameType
     @NSManaged var typeIdentifier: String
     
     @NSManaged var gameCollections: Set<GameCollection>
+    @NSManaged var previewSaveState: SaveState?
     
     var fileURL: NSURL {
         let fileURL = DatabaseManager.gamesDirectoryURL.URLByAppendingPathComponent(self.filename)

Common/Database/Model/Model.xcdatamodeld/Model.xcdatamodel/contents

@@ -15,6 +15,7 @@
         <attribute name="name" attributeType="String" syncable="YES"/>
         <attribute name="typeIdentifier" attributeType="String" syncable="YES"/>
         <relationship name="gameCollections" toMany="YES" deletionRule="Nullify" destinationEntity="GameCollection" inverseName="games" inverseEntity="GameCollection" syncable="YES"/>
+        <relationship name="previewSaveState" optional="YES" maxCount="1" deletionRule="Nullify" destinationEntity="SaveState" inverseName="previewGame" inverseEntity="SaveState" syncable="YES"/>
         <relationship name="saveStates" toMany="YES" deletionRule="Cascade" destinationEntity="SaveState" inverseName="game" inverseEntity="SaveState" syncable="YES"/>
         <uniquenessConstraints>
             <uniquenessConstraint>
@@ -40,11 +41,11 @@
             </userInfo>
         </attribute>
         <attribute name="identifier" attributeType="String" syncable="YES"/>
-        <attribute name="isPreview" attributeType="Boolean" defaultValueString="NO" syncable="YES"/>
         <attribute name="modifiedDate" attributeType="Date" syncable="YES"/>
         <attribute name="name" optional="YES" attributeType="String" syncable="YES"/>
         <attribute name="type" attributeType="Integer 16" defaultValueString="1" syncable="YES"/>
         <relationship name="game" optional="YES" maxCount="1" deletionRule="Nullify" destinationEntity="Game" inverseName="saveStates" inverseEntity="Game" syncable="YES"/>
+        <relationship name="previewGame" optional="YES" maxCount="1" deletionRule="Nullify" destinationEntity="Game" inverseName="previewSaveState" inverseEntity="Game" syncable="YES"/>
         <uniquenessConstraints>
             <uniquenessConstraint>
                 <constraint value="identifier"/>
@@ -52,7 +53,7 @@
         </uniquenessConstraints>
     </entity>
     <elements>
-        <element name="Game" positionX="-200" positionY="-72" width="128" height="148"/>
+        <element name="Game" positionX="-200" positionY="-72" width="128" height="165"/>
         <element name="GameCollection" positionX="-198" positionY="-207" width="128" height="90"/>
         <element name="SaveState" positionX="-198" positionY="113" width="128" height="165"/>
     </elements>

Common/Database/Model/SaveState.swift

@@ -17,13 +17,13 @@ extension SaveState
     {
         case filename
         case identifier
-        case isPreview
         case name
         case creationDate
         case modifiedDate
         case type
         
         case game
+        case previewGame
     }
     
     @objc enum Type: Int16
@@ -40,7 +40,6 @@ class SaveState: NSManagedObject, SaveStateType
     @NSManaged var name: String?
     @NSManaged var modifiedDate: NSDate
     @NSManaged var type: Type
-    @NSManaged var isPreview: Bool
     
     @NSManaged private(set) var filename: String
     @NSManaged private(set) var identifier: String
@@ -50,6 +49,8 @@ class SaveState: NSManagedObject, SaveStateType
     // https://forums.developer.apple.com/thread/20535
     @NSManaged var game: Game!
     
+    @NSManaged var previewGame: Game?
+    
     var fileURL: NSURL {
         let fileURL = DatabaseManager.saveStatesDirectoryURLForGame(self.game).URLByAppendingPathComponent(self.filename)
         return fileURL

Delta/Game Selection/GamesViewController.swift

@@ -130,9 +130,7 @@ class GamesViewController: UIViewController
         {
             destinationViewController.deferredPreparationHandler = { [unowned destinationViewController] in
                                 
-                let predicate = NSPredicate(format: "%K == %@ AND %K == YES", SaveState.Attributes.game.rawValue, game, SaveState.Attributes.isPreview.rawValue)
+                if let saveState = game.previewSaveState
-                
-                if let saveState = SaveState.instancesWithPredicate(predicate, inManagedObjectContext: DatabaseManager.sharedManager.managedObjectContext, type: SaveState.self).first
                 {
                     destinationViewController.emulatorCore.startEmulation()
                     destinationViewController.emulatorCore.pauseEmulation()

Delta/Pause Menu/Save States/SaveStatesViewController.swift

@@ -358,15 +358,14 @@ private extension SaveStatesViewController
                 var game = self.delegate.saveStatesViewControllerActiveEmulatorCore(self).game as! Game
                 game = backgroundContext.objectWithID(game.objectID) as! Game
                 
-                let predicate = NSPredicate(format: "%K == %@ AND %K == YES", SaveState.Attributes.game.rawValue, game, SaveState.Attributes.isPreview.rawValue)
-                
-                let previousPreviewSaveState = SaveState.instancesWithPredicate(predicate, inManagedObjectContext: backgroundContext, type: SaveState.self).first
-                previousPreviewSaveState?.isPreview = false
-                
                 if let saveState = saveState
                 {
                     let previewSaveState = backgroundContext.objectWithID(saveState.objectID) as! SaveState
-                    previewSaveState.isPreview = true
+                    game.previewSaveState = previewSaveState
+                }
+                else
+                {
+                    game.previewSaveState = nil
                 }
                 
                 backgroundContext.saveWithErrorLogging()
@@ -465,7 +464,7 @@ private extension SaveStatesViewController
         
         if self.traitCollection.forceTouchCapability == .Available
         {
-            if !saveState.isPreview
+            if saveState.game.previewSaveState != saveState
             {
                 let previewAction = Action(title: NSLocalizedString("Set as Preview Save State", comment: ""), style: .Default, action: { action in
                     self.updatePreviewSaveState(saveState)