iOS: Enable support for layered/async drawing

BREAKING-CHANGES.txt

@@ -4,6 +4,27 @@ JUCE breaking changes
 Develop
 =======
 
+Change
+------
+The functions `getComponentAsyncLayerBackedViewDisabled`
+and `setComponentAsyncLayerBackedViewDisabled` were moved into the juce
+namespace.
+
+Possible Issues
+---------------
+Code that declares these functions may fail to link.
+
+Workaround
+----------
+Move declarations of these functions into the juce namespace.
+
+Rationale
+---------
+Although the names of these functions are unlikely to collide with functions
+from other libraries, we can make such collisions much more unlikely by keeping
+JUCE code in the juce namespace.
+
+
 Change
 ------
 The `juce_blocks_basics` module was removed.

modules/juce_gui_basics/juce_gui_basics.cpp

@@ -236,6 +236,25 @@ namespace juce
  #include "native/juce_MultiTouchMapper.h"
 #endif
 
+namespace juce
+{
+
+static const juce::Identifier disableAsyncLayerBackedViewIdentifier { "disableAsyncLayerBackedView" };
+
+/** Used by the macOS and iOS peers. */
+void setComponentAsyncLayerBackedViewDisabled (juce::Component& comp, bool shouldDisableAsyncLayerBackedView)
+{
+    comp.getProperties().set (disableAsyncLayerBackedViewIdentifier, shouldDisableAsyncLayerBackedView);
+}
+
+/** Used by the macOS and iOS peers. */
+bool getComponentAsyncLayerBackedViewDisabled (juce::Component& comp)
+{
+    return comp.getProperties()[disableAsyncLayerBackedViewIdentifier];
+}
+
+} // namespace juce
+
 #if JUCE_MAC || JUCE_IOS
  #if JUCE_IOS
   #include "native/juce_ios_UIViewComponentPeer.mm"

modules/juce_gui_basics/native/juce_ios_UIViewComponentPeer.mm

@@ -583,6 +583,13 @@ UIViewComponentPeer::UIViewComponentPeer (Component& comp, int windowStyleFlags,
     view.opaque = component.isOpaque();
     view.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent: 0];
 
+   #if JUCE_COREGRAPHICS_DRAW_ASYNC
+    if (! getComponentAsyncLayerBackedViewDisabled (component))
+    {
+        [[view layer] setDrawsAsynchronously: YES];
+    }
+   #endif
+
     if (isSharedWindow)
     {
         window = [viewToAttachTo window];

modules/juce_gui_basics/native/juce_mac_NSViewComponentPeer.mm

@@ -28,22 +28,6 @@
 - (float)deviceDeltaY;
 @end
 
-//==============================================================================
-#if defined (MAC_OS_X_VERSION_10_8) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_8) \
-  && USE_COREGRAPHICS_RENDERING && JUCE_COREGRAPHICS_DRAW_ASYNC
-static const juce::Identifier disableAsyncLayerBackedViewIdentifier { "disableAsyncLayerBackedView" };
-
-void setComponentAsyncLayerBackedViewDisabled (juce::Component& comp, bool shouldDisableAsyncLayerBackedView)
-{
-    comp.getProperties().set (disableAsyncLayerBackedViewIdentifier, shouldDisableAsyncLayerBackedView);
-}
-
-bool getComponentAsyncLayerBackedViewDisabled (juce::Component& comp)
-{
-    return comp.getProperties()[disableAsyncLayerBackedViewIdentifier];
-}
-#endif
-
 //==============================================================================
 namespace juce
 {