Enabled metal on ios simulator

shell/gpu/gpu_surface_metal.h

@@ -17,7 +17,11 @@
 
 namespace flutter {
 
+#if TARGET_IPHONE_SIMULATOR
+class API_AVAILABLE(ios(13.0)) GPUSurfaceMetal : public Surface {
+#else
 class GPUSurfaceMetal : public Surface {
+#endif  // TARGET_IPHONE_SIMULATOR
  public:
   GPUSurfaceMetal(GPUSurfaceDelegate* delegate,
                   fml::scoped_nsobject<CAMetalLayer> layer,

shell/platform/darwin/ios/ios_surface.mm

@@ -39,14 +39,20 @@ bool IsIosEmbeddedViewsPreviewEnabled() {
   }
 
 #if FLUTTER_SHELL_ENABLE_METAL
-  if ([layer.get() isKindOfClass:[CAMetalLayer class]]) {
-    return std::make_unique<IOSSurfaceMetal>(
-        fml::scoped_nsobject<CAMetalLayer>(
-            reinterpret_cast<CAMetalLayer*>([layer.get() retain])),  // Metal layer
-        std::move(context),                                          // context
-        platform_views_controller                                    // platform views controller
-    );
+#if TARGET_IPHONE_SIMULATOR
+  if (@available(iOS 13.0, *)) {
+#endif  // TARGET_IPHONE_SIMULATOR
+    if ([layer.get() isKindOfClass:[CAMetalLayer class]]) {
+      return std::make_unique<IOSSurfaceMetal>(
+          fml::scoped_nsobject<CAMetalLayer>(
+              reinterpret_cast<CAMetalLayer*>([layer.get() retain])),  // Metal layer
+          std::move(context),                                          // context
+          platform_views_controller                                    // platform views controller
+      );
+    }
+#if TARGET_IPHONE_SIMULATOR
   }
+#endif  // TARGET_IPHONE_SIMULATOR
 #endif  // FLUTTER_SHELL_ENABLE_METAL
 
   return std::make_unique<IOSSurfaceSoftware>(

shell/platform/darwin/ios/ios_surface_metal.h

@@ -13,7 +13,12 @@
 
 namespace flutter {
 
+#if TARGET_IPHONE_SIMULATOR
+class API_AVAILABLE(ios(13.0)) IOSSurfaceMetal final : public IOSSurface,
+                                                       public GPUSurfaceDelegate {
+#else
 class IOSSurfaceMetal final : public IOSSurface, public GPUSurfaceDelegate {
+#endif  // TARGET_IPHONE_SIMULATOR
  public:
   IOSSurfaceMetal(fml::scoped_nsobject<CAMetalLayer> layer,
                   std::shared_ptr<IOSContext> context,

shell/platform/darwin/ios/rendering_api_selection.mm

@@ -21,26 +21,34 @@ bool ShouldUseMetalRenderer() {
   // past iOS 10.0. The processor was selected as it is the first version at which Metal was
   // supported. The iOS version floor was selected due to the availability of features used by Skia.
   bool ios_version_supports_metal = false;
+#if TARGET_IPHONE_SIMULATOR
+  if (@available(iOS 13.0, *)) {
+#else
   if (@available(iOS 10.0, *)) {
+#endif  // TARGET_IPHONE_SIMULATOR
     auto device = MTLCreateSystemDefaultDevice();
-    ios_version_supports_metal = [device supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily1_v3];
+    // We need to check if the device is here since an ios 13 simulator running on an older version
+    // of macos (below 10.15) will not actually allow metal to be used.
+    if (device != nil) {
+      ios_version_supports_metal = [device supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily1_v3];
+    }
   }
   return ios_version_supports_metal;
 }
 #endif  // FLUTTER_SHELL_ENABLE_METAL
 
 IOSRenderingAPI GetRenderingAPIForProcess() {
-#if TARGET_IPHONE_SIMULATOR
-  return IOSRenderingAPI::kSoftware;
-#endif  // TARGET_IPHONE_SIMULATOR
-
 #if FLUTTER_SHELL_ENABLE_METAL
   static bool should_use_metal = ShouldUseMetalRenderer();
   if (should_use_metal) {
     return IOSRenderingAPI::kMetal;
   }
 #endif  // FLUTTER_SHELL_ENABLE_METAL
+#if TARGET_IPHONE_SIMULATOR
+  return IOSRenderingAPI::kSoftware;
+#else
   return IOSRenderingAPI::kOpenGLES;
+#endif  // TARGET_IPHONE_SIMULATOR
 }
 
 Class GetCoreAnimationLayerClassForRenderingAPI(IOSRenderingAPI rendering_api) {
@@ -49,8 +57,15 @@ Class GetCoreAnimationLayerClassForRenderingAPI(IOSRenderingAPI rendering_api) {
       return [CALayer class];
     case IOSRenderingAPI::kOpenGLES:
       return [CAEAGLLayer class];
-#if !TARGET_IPHONE_SIMULATOR
     case IOSRenderingAPI::kMetal:
+#if TARGET_IPHONE_SIMULATOR
+      // This will always be true since we filter out this case when checking if the device
+      // supports metal.
+      if (@available(iOS 13.0, *)) {
+        return [CAMetalLayer class];
+      }
+      break;
+#else
       return [CAMetalLayer class];
 #endif  // !TARGET_IPHONE_SIMULATOR
     default:

tools/gn

@@ -217,7 +217,7 @@ def to_gn_args(args):
       gn_args['goma_dir'] = None
 
     # Enable Metal on non-simulator iOS builds.
-    if args.target_os == 'ios' and not args.simulator:
+    if args.target_os == 'ios':
       gn_args['skia_use_metal'] = True
       gn_args['shell_enable_metal'] = True
       # Bitcode enabled builds using the current version of the toolchain leak