macOS: Handle unavailable Metal device

modules/juce_gui_basics/native/juce_ios_UIViewComponentPeer.mm

@@ -1398,7 +1398,10 @@ UIViewComponentPeer::UIViewComponentPeer (Component& comp, int windowStyleFlags,
 
    #if JUCE_COREGRAPHICS_RENDER_WITH_MULTIPLE_PAINT_CALLS
     if (@available (iOS 13, *))
-        metalRenderer = std::make_unique<CoreGraphicsMetalLayerRenderer<UIView>> (view, comp.isOpaque());
+    {
+        metalRenderer = CoreGraphicsMetalLayerRenderer<UIView>::create (view, comp.isOpaque());
+        jassert (metalRenderer != nullptr);
+    }
    #endif
 
     if ((windowStyleFlags & ComponentPeer::windowRequiresSynchronousCoreGraphicsRendering) == 0)

modules/juce_gui_basics/native/juce_mac_CGMetalLayerRenderer.h

@@ -35,12 +35,11 @@ class CoreGraphicsMetalLayerRenderer
 {
 public:
     //==============================================================================
-    CoreGraphicsMetalLayerRenderer (ViewType* view, bool isOpaque)
+    static auto create (ViewType* view, bool isOpaque)
     {
-        device.reset (MTLCreateSystemDefaultDevice());
-        commandQueue.reset ([device.get() newCommandQueue]);
-
-        attach (view, isOpaque);
+        ObjCObjectHandle<id<MTLDevice>> device { MTLCreateSystemDefaultDevice() };
+        return rawToUniquePtr (device != nullptr ? new CoreGraphicsMetalLayerRenderer (device, view, isOpaque)
+                                                 : nullptr);
     }
 
     ~CoreGraphicsMetalLayerRenderer()
@@ -223,6 +222,16 @@ public:
     }
 
 private:
+    //==============================================================================
+    CoreGraphicsMetalLayerRenderer (ObjCObjectHandle<id<MTLDevice>> mtlDevice,
+                                    ViewType* view,
+                                    bool isOpaque)
+        : device (mtlDevice),
+          commandQueue ([device.get() newCommandQueue])
+    {
+        attach (view, isOpaque);
+    }
+
     //==============================================================================
     static auto alignTo (size_t n, size_t alignment)
     {

modules/juce_gui_basics/native/juce_mac_NSViewComponentPeer.mm

@@ -151,7 +151,7 @@ public:
       #if USE_COREGRAPHICS_RENDERING
        #if JUCE_COREGRAPHICS_RENDER_WITH_MULTIPLE_PAINT_CALLS
         if (@available (macOS 10.14, *))
-            metalRenderer = std::make_unique<CoreGraphicsMetalLayerRenderer<NSView>> (view, getComponent().isOpaque());
+            metalRenderer = CoreGraphicsMetalLayerRenderer<NSView>::create (view, getComponent().isOpaque());
        #endif
         if ((windowStyleFlags & ComponentPeer::windowRequiresSynchronousCoreGraphicsRendering) == 0)
         {