When creating a surface, accept either a CAMetalLayer or an

NSView/UIView in the pView member, and improve error logging.

Docs/MoltenVK_Runtime_UserGuide.md

@@ -252,6 +252,17 @@ You can enable each of these extensions by defining the `VK_USE_PLATFORM_IOS_MVK
 `VK_USE_PLATFORM_MACOS_MVK` guard macro in your compiler build settings. See the description
 of the `mvk_vulkan.h` file below for a convenient way to enable these extensions automatically.
 
+When using the `VK_MVK_macos_surface ` extension, the `pView` member of the `VkMacOSSurfaceCreateInfoMVK` 
+structure passed in the `vkCreateMacOSSurfaceMVK` function can be either an `NSView` whose layer is a 
+`CAMetalLayer`, or the `CAMetalLayer` itself. Passing the `CAMetalLayer` itself is recommended when calling
+the `vkCreateMacOSSurfaceMVK` function from outside the main application thread, as `NSView` should only be
+accessed from the main application thread.
+
+When using the `VK_MVK_ios_surface ` extension, the `pView` member of the `VkIOSSurfaceCreateInfoMVK` 
+structure passed in the `vkCreateIOSSurfaceMVK` function can be either a `UIView` whose layer is a 
+`CAMetalLayer`, or the `CAMetalLayer` itself. Passing the `CAMetalLayer` itself is recommended when 
+calling the `vkCreateIOSSurfaceMVK ` function from outside the main application thread, as `UIView` 
+should only be accessed from the main application thread.
 
 <a name="moltenvk_extension"></a>
 ### MoltenVK Extension

MoltenVK/MoltenVK/GPUObjects/MVKSurface.h

@@ -28,14 +28,14 @@
 #	define Vk_PLATFORM_SurfaceCreateInfoMVK		VkIOSSurfaceCreateInfoMVK
 #	define PLATFORM_VIEW_CLASS					UIView
 #	include <UIKit/UIView.h>
-#endif	// MVK_IOS
+#endif
 
 #ifdef VK_USE_PLATFORM_MACOS_MVK
 #	define vkCreate_PLATFORM_SurfaceMVK			vkCreateMacOSSurfaceMVK
 #	define Vk_PLATFORM_SurfaceCreateInfoMVK		VkMacOSSurfaceCreateInfoMVK
 #	define PLATFORM_VIEW_CLASS					NSView
 #	include <AppKit/NSView.h>
-#endif	// MVK_MACOS
+#endif
 
 #import <Metal/Metal.h>
 #import <QuartzCore/CAMetalLayer.h>

MoltenVK/MoltenVK/GPUObjects/MVKSurface.mm

@@ -26,18 +26,41 @@
 
 #pragma mark Construction
 
+#ifdef VK_USE_PLATFORM_IOS_MVK
+static const char* mvkSurfaceCreateFuncName = "vkCreateIOSSurfaceMVK";
+static const char* mvkSurfaceCreateStructName = "VkIOSSurfaceCreateInfoMVK";
+static const char* mvkViewClassName = "UIView";
+#endif
+
+#ifdef VK_USE_PLATFORM_MACOS_MVK
+static const char* mvkSurfaceCreateFuncName = "vkCreateMacOSSurfaceMVK";
+static const char* mvkSurfaceCreateStructName = "VkMacOSSurfaceCreateInfoMVK";
+static const char* mvkViewClassName = "NSView";
+#endif
+
+// pCreateInfo->pView can be either a CAMetalLayer or a view (NSView/UIView).
 MVKSurface::MVKSurface(MVKInstance* mvkInstance,
 					   const Vk_PLATFORM_SurfaceCreateInfoMVK* pCreateInfo,
 					   const VkAllocationCallbacks* pAllocator) {
 
-	__block CALayer* viewLayer = nil;
-	mvkDispatchToMainAndWait(^{ viewLayer = ((PLATFORM_VIEW_CLASS*)pCreateInfo->pView).layer; });
-    if ( [viewLayer isKindOfClass: [CAMetalLayer class]] ) {
-        _mtlCAMetalLayer = (CAMetalLayer*)[viewLayer retain];		// retained
-    } else {
-        setConfigurationResult(mvkNotifyErrorWithText(VK_ERROR_INITIALIZATION_FAILED, "On-screen rendering requires a view that is backed by a layer of type CAMetalLayer."));
-        _mtlCAMetalLayer = nil;
-    }
+	// Get the platform object contained in pView
+	id<NSObject> obj = (id<NSObject>)pCreateInfo->pView;
+
+	// If it's a view (NSView/UIView), extract the layer, otherwise assume it's already a CAMetalLayer.
+	if ([obj isKindOfClass: [PLATFORM_VIEW_CLASS class]]) {
+		if ( !NSThread.isMainThread ) {
+			MVKLogInfo("%s(): You are not calling this function from the main thread. %s should only be accessed from the main thread. When using this function outside the main thread, consider passing the CAMetalLayer itself in %s::pView, instead of the %s.", mvkSurfaceCreateFuncName, mvkViewClassName, mvkSurfaceCreateStructName, mvkViewClassName);
+		}
+		obj = ((PLATFORM_VIEW_CLASS*)obj).layer;
+	}
+
+	// Confirm that we were provided with a CAMetalLayer
+	if ([obj isKindOfClass: [CAMetalLayer class]]) {
+		_mtlCAMetalLayer = (CAMetalLayer*)[obj retain];		// retained
+	} else {
+		setConfigurationResult(mvkNotifyErrorWithText(VK_ERROR_INITIALIZATION_FAILED, "%s(): On-screen rendering requires a layer of type CAMetalLayer.", mvkSurfaceCreateFuncName));
+		_mtlCAMetalLayer = nil;
+	}
 }
 
 MVKSurface::~MVKSurface() {

MoltenVK/scripts/create_dylib_ios.sh

@@ -26,7 +26,7 @@ clang \
 -Wno-incompatible-sysroot \
 -isysroot ${SDK_DIR} \
 -iframework ${MVK_SYS_FWK_DIR}  \
--framework Metal ${MVK_IOSURFACE_FWK} -framework UIKit -framework QuartzCore -framework Foundation \
+-framework Metal ${MVK_IOSURFACE_FWK} -framework UIKit -framework QuartzCore -framework UIKit -framework Foundation \
 --library-directory ${MVK_USR_LIB_DIR} \
 -lSystem  -lc++ \
 -o "${MVK_BUILT_PROD_PATH}/${MVK_DYLIB_NAME}" \

MoltenVK/scripts/create_dylib_macos.sh

@@ -17,7 +17,7 @@ clang \
 -Wno-incompatible-sysroot \
 -isysroot ${SDK_DIR} \
 -iframework ${MVK_SYS_FWK_DIR}  \
--framework Metal -framework IOSurface -framework IOKit -framework QuartzCore -framework Foundation \
+-framework Metal -framework IOSurface -framework IOKit -framework QuartzCore -framework AppKit -framework Foundation \
 --library-directory ${MVK_USR_LIB_DIR} \
 -lSystem  -lc++ \
 -o "${MVK_BUILT_PROD_PATH}/${MVK_DYLIB_NAME}" \