Refactors previewing GameViewController logic into new PreviewGameViewController

Cores/DeltaCore

@@ -1 +1 @@
-Subproject commit d9b61b60c23286a4758bab06ed4a89de641f2628
+Subproject commit d4895367427ffed6ef1fd04e60868cf799fb3371

Delta.xcodeproj/project.pbxproj

@@ -13,6 +13,8 @@
 		BF090CF41B490D8300DCAB45 /* UIDevice+Vibration.m in Sources */ = {isa = PBXBuildFile; fileRef = BF090CF31B490D8300DCAB45 /* UIDevice+Vibration.m */; };
 		BF0CDDAD1C8155D200640168 /* LoadImageOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF0CDDAC1C8155D200640168 /* LoadImageOperation.swift */; };
 		BF107EC41BF413F000E0C32C /* GamesViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF107EC31BF413F000E0C32C /* GamesViewController.swift */; };
+		BF13A7561D5D29B0000BB055 /* PreviewGameViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF13A7551D5D29B0000BB055 /* PreviewGameViewController.swift */; };
+		BF13A7581D5D2FD9000BB055 /* EmulatorCore+Cheats.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF13A7571D5D2FD9000BB055 /* EmulatorCore+Cheats.swift */; };
 		BF172AEB1C68986300C26774 /* NSManagedObjectContext+Conveniences.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF172AEA1C68986300C26774 /* NSManagedObjectContext+Conveniences.swift */; };
 		BF1FB1861C5EE643007E2494 /* SaveState.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF1FB1831C5EE643007E2494 /* SaveState.swift */; };
 		BF27CC8E1BC9FEA200A20D89 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = BF6BB2451BB73FE800CCF94A /* Assets.xcassets */; };
@@ -99,6 +101,8 @@
 		BF090CF31B490D8300DCAB45 /* UIDevice+Vibration.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UIDevice+Vibration.m"; sourceTree = "<group>"; };
 		BF0CDDAC1C8155D200640168 /* LoadImageOperation.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = LoadImageOperation.swift; path = Components/LoadImageOperation.swift; sourceTree = "<group>"; };
 		BF107EC31BF413F000E0C32C /* GamesViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GamesViewController.swift; sourceTree = "<group>"; };
+		BF13A7551D5D29B0000BB055 /* PreviewGameViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PreviewGameViewController.swift; sourceTree = "<group>"; };
+		BF13A7571D5D2FD9000BB055 /* EmulatorCore+Cheats.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "EmulatorCore+Cheats.swift"; sourceTree = "<group>"; };
 		BF172AEA1C68986300C26774 /* NSManagedObjectContext+Conveniences.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "NSManagedObjectContext+Conveniences.swift"; sourceTree = "<group>"; };
 		BF1FB1831C5EE643007E2494 /* SaveState.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SaveState.swift; sourceTree = "<group>"; };
 		BF27CC861BC9E3C600A20D89 /* Delta.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.xml; path = Delta.entitlements; sourceTree = "<group>"; };
@@ -189,6 +193,7 @@
 				BF797A2C1C2D339F00F1A000 /* UILabel+FontSize.swift */,
 				BF7AE8091C2E8C7600B1B5BC /* UIColor+Delta.swift */,
 				BFCEA67D1D56FF640061A534 /* UIViewControllerContextTransitioning+Conveniences.swift */,
+				BF13A7571D5D2FD9000BB055 /* EmulatorCore+Cheats.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";
@@ -412,6 +417,7 @@
 			isa = PBXGroup;
 			children = (
 				BF63BDE91D389EEB00FCB040 /* GameViewController.swift */,
+				BF13A7551D5D29B0000BB055 /* PreviewGameViewController.swift */,
 			);
 			path = Emulation;
 			sourceTree = "<group>";
@@ -573,6 +579,7 @@
 				BF7AE8241C2E984300B1B5BC /* GridCollectionViewLayout.swift in Sources */,
 				BF1FB1861C5EE643007E2494 /* SaveState.swift in Sources */,
 				BFA0D1271D3AE1F600565894 /* GameViewController.swift in Sources */,
+				BF13A7581D5D2FD9000BB055 /* EmulatorCore+Cheats.swift in Sources */,
 				BF31878B1D489AAA00BD020D /* CheatValidator.swift in Sources */,
 				BFB141181BE46934004FBF46 /* GameCollectionViewDataSource.swift in Sources */,
 				BFFC46201D59823500AF2CC6 /* InitialGamesStoryboardSegue.swift in Sources */,
@@ -605,6 +612,7 @@
 				BF0CDDAD1C8155D200640168 /* LoadImageOperation.swift in Sources */,
 				BF107EC41BF413F000E0C32C /* GamesViewController.swift in Sources */,
 				BF172AEB1C68986300C26774 /* NSManagedObjectContext+Conveniences.swift in Sources */,
+				BF13A7561D5D29B0000BB055 /* PreviewGameViewController.swift in Sources */,
 				BFCEA67E1D56FF640061A534 /* UIViewControllerContextTransitioning+Conveniences.swift in Sources */,
 				BFFC461E1D59823500AF2CC6 /* GamesPresentationController.swift in Sources */,
 				BF5E7F441B9A650B00AE44F8 /* SettingsViewController.swift in Sources */,

Delta/Emulation/GameViewController.swift

@@ -39,19 +39,10 @@ class GameViewController: DeltaCore.GameViewController
             self.emulatorCore?.removeObserver(self, forKeyPath: #keyPath(EmulatorCore.state), context: &kvoContext)
         }
         didSet {
-            guard let emulatorCore = self.emulatorCore else { return }
+            self.emulatorCore?.addObserver(self, forKeyPath: #keyPath(EmulatorCore.state), options: [.old], context: &kvoContext)
-            self.preferredContentSize = emulatorCore.preferredRenderingSize
-            
-            emulatorCore.addObserver(self, forKeyPath: #keyPath(EmulatorCore.state), options: [.old], context: &kvoContext)
         }
     }
     
-    // If non-nil, will override the default preview action items returned in previewActionItems()
-    var overridePreviewActionItems: [UIPreviewActionItem]?
-    
-    // Set to true to handle automatically updating auto save state
-    var updatesAutoSaveState = false
-    
     //MARK: - Private Properties -
     private var pauseViewController: PauseViewController?
     private var pausingGameController: GameController?
@@ -86,26 +77,6 @@ class GameViewController: DeltaCore.GameViewController
     private var sustainButtonsBlurView: UIVisualEffectView!
     private var sustainButtonsBackgroundView: RSTBackgroundView!
     
-    override var previewActionItems: [UIPreviewActionItem]
-    {
-        if let previewActionItems = self.overridePreviewActionItems
-        {
-            return previewActionItems
-        }
-        
-        guard let game = self.game as? Game else { return [] }
-        
-        let presentingViewController = self.presentingViewController
-        
-        let launchGameAction = UIPreviewAction(title: NSLocalizedString("Launch \(game.name)", comment: ""), style: .default) { (action, viewController) in
-            // Delaying until next run loop prevents self from being dismissed immediately
-            DispatchQueue.main.async {
-                presentingViewController?.present(viewController, animated: true, completion: nil)
-            }
-        }
-        return [launchGameAction]
-    }
-    
     required init()
     {
         self.reactivateSustainedInputsQueue = OperationQueue()
@@ -349,7 +320,7 @@ extension GameViewController
         
         if previousState == .stopped
         {
-            self.updateCheats()
+            self.emulatorCore?.updateCheats()
         }
     }
 }
@@ -397,8 +368,6 @@ extension GameViewController: SaveStatesViewControllerDelegate
 {
     private func updateAutoSaveState()
     {        
-        guard self.updatesAutoSaveState else { return }
-        
         // If pausedSaveState exists and has already been saved, don't update auto save state
         // This prevents us from filling our auto save state slots with the same save state
         let savedPausedSaveState = self.pausedSaveState?.isSaved ?? false
@@ -566,7 +535,7 @@ extension GameViewController: SaveStatesViewControllerDelegate
             print(error)
         }
         
-        self.updateCheats()
+        self.emulatorCore?.updateCheats()
         
         self.pauseViewController?.dismiss()
     }
@@ -578,67 +547,13 @@ extension GameViewController: CheatsViewControllerDelegate
 {
     func cheatsViewController(_ cheatsViewController: CheatsViewController, activateCheat cheat: Cheat)
     {
-        self.activate(cheat)
+        self.emulatorCore?.activateCheatWithErrorLogging(cheat)
     }
     
     func cheatsViewController(_ cheatsViewController: CheatsViewController, deactivateCheat cheat: Cheat)
     {
         self.emulatorCore?.deactivate(cheat)
     }
-    
-    private func activate(_ cheat: Cheat)
-    {
-        do
-        {
-            try self.emulatorCore?.activate(cheat)
-        }
-        catch EmulatorCore.CheatError.invalid
-        {
-            print("Invalid cheat:", cheat.name, cheat.code)
-        }
-        catch let error as NSError
-        {
-            print("Unknown Cheat Error:", error, cheat.name, cheat.code)
-        }
-    }
-    
-    private func updateCheats()
-    {
-        guard let game = self.game as? Game else { return }
-        
-        let running = (self.emulatorCore?.state == .running)
-        
-        if running
-        {
-            // Core MUST be paused when activating cheats, or else race conditions could crash the core
-            self.pauseEmulation()
-        }
-        
-        let backgroundContext = DatabaseManager.shared.newBackgroundContext()
-        backgroundContext.performAndWait {
-            
-            let predicate = NSPredicate(format: "%K == %@", Cheat.Attributes.game.rawValue, game)
-            
-            let cheats = Cheat.instancesWithPredicate(predicate, inManagedObjectContext: backgroundContext, type: Cheat.self)
-            for cheat in cheats
-            {
-                if cheat.enabled
-                {
-                    self.activate(cheat)
-                }
-                else
-                {
-                    self.emulatorCore?.deactivate(cheat)
-                }
-            }
-        }
-        
-        if running
-        {
-            self.resumeEmulation()
-        }
-        
-    }
 }
 
 //MARK: - Sustain Buttons -

Delta/Emulation/PreviewGameViewController.swift

@@ -0,0 +1,176 @@
+//
+//  PreviewGameViewController.swift
+//  Delta
+//
+//  Created by Riley Testut on 8/11/16.
+//  Copyright © 2016 Riley Testut. All rights reserved.
+//
+
+import UIKit
+
+import DeltaCore
+
+private var kvoContext = 0
+
+class PreviewGameViewController: DeltaCore.GameViewController
+{
+    // If non-nil, will override the default preview action items returned in previewActionItems()
+    var overridePreviewActionItems: [UIPreviewActionItem]?
+    
+    // Save state to be loaded upon preview
+    var previewSaveState: SaveStateProtocol?
+    
+    // Initial image to be shown while loading
+    var previewImage: UIImage? {
+        didSet {
+            self.updatePreviewImage()
+        }
+    }
+    
+    private var emulatorCoreQueue = DispatchQueue(label: "com.rileytestut.Delta.PreviewGameViewController.emulatorCoreQueue", qos: .userInitiated)
+    
+    override var game: GameProtocol? {
+        willSet {
+            self.emulatorCore?.removeObserver(self, forKeyPath: #keyPath(EmulatorCore.state), context: &kvoContext)
+        }
+        didSet {
+            guard let emulatorCore = self.emulatorCore else {
+                self.preferredContentSize = CGSize.zero
+                return
+            }
+            
+            emulatorCore.addObserver(self, forKeyPath: #keyPath(EmulatorCore.state), options: [.old], context: &kvoContext)
+            
+            self.preferredContentSize = emulatorCore.preferredRenderingSize
+        }
+    }
+    
+    override var previewActionItems: [UIPreviewActionItem] {
+        guard let previewActionItems = self.overridePreviewActionItems else { return [] }
+        return previewActionItems
+    }
+    
+    deinit
+    {
+        self.emulatorCore?.removeObserver(self, forKeyPath: #keyPath(EmulatorCore.state), context: &kvoContext)
+    }
+}
+
+//MARK: - UIViewController -
+/// UIViewController
+extension PreviewGameViewController
+{
+    override func viewDidLoad()
+    {
+        super.viewDidLoad()
+        
+        self.controllerView.isHidden = true
+        
+        // Temporarily prevent emulatorCore from updating gameView to prevent flicker of black, or other visual glitches
+        self.emulatorCore?.remove(self.gameView)
+    }
+
+    override func viewDidAppear(_ animated: Bool)
+    {
+        super.viewDidAppear(animated)
+        
+        self.emulatorCoreQueue.async {
+            self.emulatorCore?.resume()
+        }
+    }
+    
+    override func viewWillDisappear(_ animated: Bool)
+    {
+        super.viewWillDisappear(animated)
+        
+        // Pause in viewWillDisappear and not viewDidDisappear like DeltaCore.GameViewController so the audio cuts off earlier if being dismissed
+        self.emulatorCore?.pause()
+    }
+    
+    override func viewDidLayoutSubviews()
+    {
+        super.viewDidLayoutSubviews()
+        
+        // Need to update in viewDidLayoutSubviews() to ensure bounds of gameView are not CGRect.zero
+        self.updatePreviewImage()
+    }
+
+    override func didReceiveMemoryWarning()
+    {
+        super.didReceiveMemoryWarning()
+        // Dispose of any resources that can be recreated.
+    }
+    
+    override func observeValue(forKeyPath keyPath: String?, of object: AnyObject?, change: [NSKeyValueChangeKey : AnyObject]?, context: UnsafeMutablePointer<Void>?)
+    {
+        guard context == &kvoContext else { return super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context) }
+        
+        guard
+            let rawValue = change?[.oldKey] as? Int,
+            let previousState = EmulatorCore.State(rawValue: rawValue),
+            let state = self.emulatorCore?.state
+        else { return }
+        
+        if previousState == .stopped, state == .running
+        {
+            self.emulatorCoreQueue.sync {
+                if self.isAppearing
+                {
+                    // Pause to prevent it from starting before visible (in case user peeked slowly)
+                    self.emulatorCore?.pause()
+                }
+                
+                self.preparePreview()
+            }
+        }
+    }
+}
+
+//MARK: - Private -
+private extension PreviewGameViewController
+{
+    func updatePreviewImage()
+    {        
+        if let previewImage = self.previewImage
+        {
+            self.gameView?.inputImage = CIImage(image: previewImage)
+        }
+        else
+        {
+            self.gameView?.inputImage = nil
+        }
+    }
+    
+    func preparePreview()
+    {
+        var previewSaveState = self.previewSaveState
+        
+        if let saveState = self.previewSaveState as? SaveState
+        {
+            saveState.managedObjectContext?.performAndWait {
+                previewSaveState = DeltaCore.SaveState(fileURL: saveState.fileURL, gameType: saveState.gameType)
+            }
+        }
+        
+        if let saveState = previewSaveState
+        {
+            do
+            {
+                try self.emulatorCore?.load(saveState)
+            }
+            catch EmulatorCore.SaveStateError.doesNotExist
+            {
+                print("Save State does not exist.")
+            }
+            catch
+            {
+                print(error)
+            }
+        }
+        
+        self.emulatorCore?.updateCheats()
+        
+        // Re-enable emulatorCore to update gameView again
+        self.emulatorCore?.add(self.gameView)
+    }
+}

Delta/Extensions/EmulatorCore+Cheats.swift

@@ -0,0 +1,66 @@
+//
+//  EmulatorCore+Cheats.swift
+//  Delta
+//
+//  Created by Riley Testut on 8/11/16.
+//  Copyright © 2016 Riley Testut. All rights reserved.
+//
+
+import DeltaCore
+
+extension EmulatorCore
+{
+    func activateCheatWithErrorLogging(_ cheat: Cheat)
+    {
+        do
+        {
+            try self.activate(cheat)
+        }
+        catch EmulatorCore.CheatError.invalid
+        {
+            print("Invalid cheat:", cheat.name, cheat.code)
+        }
+        catch
+        {
+            print("Unknown Cheat Error:", error, cheat.name, cheat.code)
+        }
+    }
+    
+    func updateCheats()
+    {
+        guard let game = self.game as? Game else { return }
+        
+        let running = (self.state == .running)
+        
+        if running
+        {
+            // Core MUST be paused when activating cheats, or else race conditions could crash the core
+            self.pause()
+        }
+        
+        let backgroundContext = DatabaseManager.shared.newBackgroundContext()
+        backgroundContext.performAndWait {
+            
+            let predicate = NSPredicate(format: "%K == %@", Cheat.Attributes.game.rawValue, game)
+            
+            let cheats = Cheat.instancesWithPredicate(predicate, inManagedObjectContext: backgroundContext, type: Cheat.self)
+            for cheat in cheats
+            {
+                if cheat.enabled
+                {
+                    self.activateCheatWithErrorLogging(cheat)
+                }
+                else
+                {
+                    self.deactivate(cheat)
+                }
+            }
+        }
+        
+        if running
+        {
+            self.resume()
+        }
+
+    }
+}

Delta/Launch/LaunchViewController.swift

@@ -43,6 +43,5 @@ class LaunchViewController: UIViewController
         guard segue.identifier == "embedGameViewController" else { return }
         
         self.gameViewController = segue.destination as! GameViewController
-        self.gameViewController.updatesAutoSaveState = true
     }
 }

Delta/Pause Menu/Save States/SaveStatesViewController.swift

@@ -65,8 +65,6 @@ class SaveStatesViewController: UICollectionViewController
     
     private let dateFormatter: DateFormatter
     
-    private let previewGameViewController = GameViewController()
-    
     required init?(coder aDecoder: NSCoder)
     {
         self.dateFormatter = DateFormatter()
@@ -123,8 +121,7 @@ extension SaveStatesViewController
         let longPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(SaveStatesViewController.handleLongPressGesture(_:)))
         self.collectionView?.addGestureRecognizer(longPressGestureRecognizer)
 
-        // Pre-initialize previewGameViewController with game and start/pause emulation to ensure previewingContext(_:viewControllerForLocation:) callback doesn't take too long + break 3D Touch animation
+        self.prepareEmulatorCoreSaveState()
-        self.preparePreviewGameViewController()
         
         self.registerForPreviewing(with: self, sourceView: self.collectionView!)
         
@@ -286,23 +283,13 @@ private extension SaveStatesViewController
     
     func updateSaveState(_ saveState: SaveState)
     {
-        // Stop previewGameViewController.emulatorCore, and switch to self.emulatorCore
+        // Switch back to self.emulatorCore
         self.prepareEmulatorCore()
         
         saveState.managedObjectContext?.performAndWait {
             self.delegate?.saveStatesViewController(self, updateSaveState: saveState)
             saveState.managedObjectContext?.saveWithErrorLogging()
         }
-        
-        DispatchQueue.main.async {
-            // Only restart self.previewGameViewController.emulatorCore if we're not being dismissed
-            if !self.isDisappearing
-            {
-                self.emulatorCore?.stop()
-                self.previewGameViewController.emulatorCore?.start()
-                self.previewGameViewController.emulatorCore?.pause()
-            }
-        }
     }
     
     func loadSaveState(_ saveState: SaveStateProtocol)
@@ -492,9 +479,14 @@ private extension SaveStatesViewController
     
     func resetEmulatorCoreIfNeeded()
     {
-        guard let saveState = self.emulatorCoreSaveState else { return }
+        // Kinda hacky, but isMovingFromParentViewController only returns yes when popping off navigation controller, and not being dismissed modally
+        // Because of this, this is only run when the user returns to PauseMenuViewController, and not when they choose a save state to load
+        if self.isMovingFromParentViewController
+        {
+            self.prepareEmulatorCore()
+        }
         
-        defer
+        if let saveState = self.emulatorCoreSaveState
         {
             // Remove temporary save state file
             do
@@ -506,76 +498,57 @@ private extension SaveStatesViewController
                 print(error)
             }
         }
-        
-        self.previewGameViewController.emulatorCore?.stop()
-        
-        // Kinda hacky, but isMovingFromParentViewController only returns yes when popping off navigation controller, and not being dismissed modally
-        // Because of this, this is only run when the user returns to PauseMenuViewController, and not when they choose a save state to load
-        if self.isMovingFromParentViewController
-        {
-            self.prepareEmulatorCore()
-        }
     }
     
     func prepareEmulatorCore()
     {
-        self.previewGameViewController.emulatorCore?.stop()
-        
         // We stopped emulation for 3D Touch, so now we must resume emulation and load the save state we made to make it seem like it was never stopped
-        if let emulatorCore = self.emulatorCore
+        guard let emulatorCore = self.emulatorCore else { return }
+        
+        // Temporarily disable video rendering to prevent flickers
+        emulatorCore.videoManager.isEnabled = false
+        
+        // Load the save state we stored a reference to
+        emulatorCore.start()
+        emulatorCore.pause()
+        
+        if let saveState = self.emulatorCoreSaveState
         {
-            // Temporarily disable video rendering to prevent flickers
+            do
-            emulatorCore.videoManager.isEnabled = false
-            
-            // Load the save state we stored a reference to
-            emulatorCore.start()
-            emulatorCore.pause()
-            
-            if let saveState = self.emulatorCoreSaveState
             {
-                do
+                try emulatorCore.load(saveState)
-                {
+            }
-                    try emulatorCore.load(saveState)
+            catch EmulatorCore.SaveStateError.doesNotExist
-                }
+            {
-                catch EmulatorCore.SaveStateError.doesNotExist
+                print("Save State does not exist.")
-                {
+            }
-                    print("Save State does not exist.")
+            catch let error as NSError
-                }
+            {
-                catch let error as NSError
+                print(error)
-                {
-                    print(error)
-                }
             }
-            
-            // Re-enable video rendering
-            emulatorCore.videoManager.isEnabled = true
         }
+        
+        // Re-enable video rendering
+        emulatorCore.videoManager.isEnabled = true
     }
 }
 
 //MARK: - 3D Touch -
 extension SaveStatesViewController: UIViewControllerPreviewingDelegate
 {
-    private func preparePreviewGameViewController()
+    private func prepareEmulatorCoreSaveState()
     {
-        if let emulatorCore = self.emulatorCore
+        guard let emulatorCore = self.emulatorCore else { return }
+        
+        // Store reference to current game state before we stop emulation so we can resume it if user decides to not load a save state
+        
+        let fileURL = FileManager.uniqueTemporaryURL()
+        self.emulatorCoreSaveState = emulatorCore.saveSaveState(to: fileURL)
+        
+        if self.emulatorCoreSaveState != nil
         {
-            // Store reference to current game state before we stop emulation so we can resume it if user decides to not load a save state
-            
-            let fileURL = FileManager.uniqueTemporaryURL()
-            self.emulatorCoreSaveState = emulatorCore.saveSaveState(to: fileURL)
-            
-            guard self.emulatorCoreSaveState != nil else { return }
-            
             emulatorCore.stop()
         }
-        
-        self.previewGameViewController.loadViewIfNeeded()
-        self.previewGameViewController.controllerView.isHidden = true
-        
-        self.previewGameViewController.game = self.game
-        self.previewGameViewController.emulatorCore?.start()
-        self.previewGameViewController.emulatorCore?.pause()
     }
     
     func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController?
@@ -589,37 +562,28 @@ extension SaveStatesViewController: UIViewControllerPreviewingDelegate
         previewingContext.sourceRect = layoutAttributes.frame
         
         let saveState = self.fetchedResultsController.object(at: indexPath) as! SaveState
+        let actions = self.actionsForSaveState(saveState)?.lazy.filter{ $0.style != .cancel }.map{ $0.previewAction } ?? []
+        let previewImage = self.imageCache.object(forKey: saveState.imageFileURL) ?? UIImage(contentsOfFile: saveState.imageFileURL.path)
         
-        do
+        let previewGameViewController = PreviewGameViewController()
-        {
+        previewGameViewController.game = self.game
-            try self.previewGameViewController.emulatorCore?.load(saveState)
+        previewGameViewController.overridePreviewActionItems = actions
+        previewGameViewController.previewSaveState = saveState
+        previewGameViewController.previewImage = previewImage
         
-            let actions = self.actionsForSaveState(saveState)?.lazy.filter{ $0.style != .cancel }.map{ $0.previewAction } ?? []
+        return previewGameViewController
-            self.previewGameViewController.overridePreviewActionItems = Array(actions)
-            
-            return self.previewGameViewController
-        }
-        catch EmulatorCore.SaveStateError.doesNotExist
-        {
-            print("Save State \(saveState.name) does not exist.")
-        }
-        catch let error as NSError
-        {
-            print(error)
-        }
-        
-        return nil
     }
     
     func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController)
     {
-        let gameViewController = viewControllerToCommit as! GameViewController
+        let gameViewController = viewControllerToCommit as! PreviewGameViewController        
-        
         gameViewController.emulatorCore?.pause()
         
         let fileURL = FileManager.uniqueTemporaryURL()
         if let saveState = gameViewController.emulatorCore?.saveSaveState(to: fileURL)
         {
+            gameViewController.emulatorCore?.stop()
+            
             self.loadSaveState(saveState)
             
             do