diff --git a/NesKit/NesLayer.m b/NesKit/NesLayer.m
index e110c90..d5ec8e0 100644
--- a/NesKit/NesLayer.m
+++ b/NesKit/NesLayer.m
@@ -14,12 +14,16 @@
 - (instancetype)initWithNesSystem:(NesSystem*)system {
     if(self = [super init]) {
         self.system = system;
+        self.contentsGravity = kCAGravityResizeAspect;
+        
         _timer = [NSTimer timerWithTimeInterval:1.0/60.0 repeats:YES block:^(NSTimer * _Nonnull timer) {
             if(self.system) {
-                self.contents = self.system.frame;
+                self.contents = (__bridge id _Nullable)(self.system.frame);
                 [self.system stepToNextFrame];
             }
         }];
+        
+        [[NSRunLoop currentRunLoop] addTimer:_timer forMode:NSDefaultRunLoopMode];
     }
     return self;
 }
diff --git a/NesKit/NesSystem.mm b/NesKit/NesSystem.mm
index e47b82e..30cebef 100644
--- a/NesKit/NesSystem.mm
+++ b/NesKit/NesSystem.mm
@@ -28,24 +28,28 @@
         
         size_t frameBufferSize = nes::Ppu::SCREEN_WIDTH * nes::Ppu::SCREEN_HEIGHT * sizeof(nes::Pixel);
         
-        _system->setNewFrameCallback([&](auto frameBuffer) {
+        _system->setNewFrameCallback([frameBufferSize, self](auto frameBuffer) {
             _runEmulation = NO;
             
             CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, (void*)frameBuffer, frameBufferSize, NULL);
             CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
-            _frame = CGImageCreate(nes::Ppu::SCREEN_WIDTH,
-                                   nes::Ppu::SCREEN_HEIGHT,
-                                   8,
-                                   sizeof(nes::Pixel)*8,
-                                   nes::Ppu::SCREEN_WIDTH * sizeof(nes::Pixel),
-                                   colorspace,
-                                   kCGBitmapByteOrderDefault,
-                                   dataProvider,
-                                   NULL,
-                                   true,
-                                   kCGRenderingIntentDefault);
+            CGImageRef image = CGImageCreate(nes::Ppu::SCREEN_WIDTH,
+                                             nes::Ppu::SCREEN_HEIGHT,
+                                             8,
+                                             sizeof(nes::Pixel)*8,
+                                             nes::Ppu::SCREEN_WIDTH * sizeof(nes::Pixel),
+                                             colorspace,
+                                             kCGImageAlphaPremultipliedLast,
+                                             dataProvider,
+                                             NULL,
+                                             true,
+                                             kCGRenderingIntentDefault);
             CGDataProviderRelease(dataProvider);
             CGColorSpaceRelease(colorspace);
+            
+            dispatch_async(dispatch_get_main_queue(), ^{
+                _frame = image;
+            });
         });
     }
     return self;
@@ -54,16 +58,18 @@
 - (void)runRom:(NSURL*)url {
     _system->insertCartridge([url fileSystemRepresentation]);
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-        [_condition lock];
-        while (!_runEmulation) {
-            [_condition wait];
+        while(TRUE) {
+            [_condition lock];
+            while (!_runEmulation) {
+                [_condition wait];
+            }
+            
+            while(_runEmulation) {
+                _system->tick();
+            }
+            
+            [_condition unlock];
         }
-        
-        while(_runEmulation) {
-            _system->tick();
-        }
-        
-        [_condition unlock];
     });
 }
 
diff --git a/NesKit/include/NesKit.h b/NesKit/include/NesKit.h
index 2088bce..c31b429 100644
--- a/NesKit/include/NesKit.h
+++ b/NesKit/include/NesKit.h
@@ -9,5 +9,6 @@
 #define NesKit_h
 
 #import "../NesSystem.h"
+#import "../NesLayer.h"
 
 #endif /* Header_h */
diff --git a/examples/NesApp/NesApp/ViewController.swift b/examples/NesApp/NesApp/ViewController.swift
index 4ae6ebc..0ac3816 100644
--- a/examples/NesApp/NesApp/ViewController.swift
+++ b/examples/NesApp/NesApp/ViewController.swift
@@ -8,14 +8,65 @@
 import UIKit
 import NesKit
 
+class NesView: UIView {
+    
+    let nesLayer: NesLayer
+    
+    init(system: NesSystem) {
+        self.nesLayer = NesLayer(nesSystem: system)
+        super.init(frame: .zero)
+        
+        self.layer.addSublayer(self.nesLayer)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        
+        self.nesLayer.frame = self.layer.frame
+    }
+}
+
 class ViewController: UIViewController {
     
-    var system = NesSystem()
+    let system = NesSystem()
+    lazy var nesView = NesView(system: system)
 
     override func viewDidLoad() {
         super.viewDidLoad()
+        
+        view.addSubview(nesView)
+        
+        nesView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            nesView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            nesView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            nesView.topAnchor.constraint(equalTo: view.topAnchor),
+            nesView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
+        ])
+        
+        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
+            self.openFilePicker()
+        }
     }
 
-
+    func openFilePicker() {
+        let documentPicker = UIDocumentPickerViewController(forOpeningContentTypes: [.data])
+        documentPicker.delegate = self
+        documentPicker.modalPresentationStyle = .overFullScreen
+        documentPicker.allowsMultipleSelection = false
+        present(documentPicker, animated: true)
+    }
+}
+
+extension ViewController: UIDocumentPickerDelegate {
+    
+    func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) {
+        print("Did pick document at: ", url)
+        system.runRom(url.path(percentEncoded: false))
+    }
 }
 
diff --git a/src/Cartridge.cpp b/src/Cartridge.cpp
index 241adfe..d5e8577 100644
--- a/src/Cartridge.cpp
+++ b/src/Cartridge.cpp
@@ -28,6 +28,7 @@ namespace nes {
         _chrRom = std::span<uint8_t>(_romData.get() + sizeof(RomHeader) + prgSize, chrSize);
 
         _mapper = std::make_unique<Mapper0>(_header->prgChunks, _header->chrChunks);
+        _mirroring = _header->flags.mirroring == 0 ? Mirroring::Horizontal : Mirroring::Vertical;
     }
 
     uint8_t Cartridge::readPrg(uint16_t address) {
@@ -41,7 +42,7 @@ namespace nes {
     }
 
     Cartridge::Mirroring Cartridge::mirroring() const {
-        return _header->flags.mirroring == 0 ? Mirroring::Horizontal : Mirroring::Vertical;
+        return _mirroring;
     }
 
 }
diff --git a/src/Cartridge.h b/src/Cartridge.h
index 7ef7e95..a6f4542 100644
--- a/src/Cartridge.h
+++ b/src/Cartridge.h
@@ -53,6 +53,9 @@ namespace nes {
         RomHeader* _header;
         std::span<uint8_t> _prgRom;
         std::span<uint8_t> _chrRom;
+        
+    private:
+        Mirroring _mirroring;
     };
 
 }