[OSX] correctly use UTF8 encoded text for passing strings.

SetTitle on Window, SetText on Clipboard.

native/Avalonia.Native/inc/avalonia-native.h

@@ -216,7 +216,7 @@ AVNCOM(IAvnWindow, 04) : virtual IAvnWindowBase
     virtual HRESULT ShowDialog (IUnknown**ppv) = 0;
     virtual HRESULT SetCanResize(bool value) = 0;
     virtual HRESULT SetHasDecorations(bool value) = 0;
-    virtual HRESULT SetTitle (const char* title) = 0;
+    virtual HRESULT SetTitle (void* utf8Title) = 0;
     virtual HRESULT SetTitleBarColor (AvnColor color) = 0;
     virtual HRESULT SetWindowState(AvnWindowState state) = 0;
     virtual HRESULT GetWindowState(AvnWindowState*ret) = 0;
@@ -322,7 +322,7 @@ AVNCOM(IAvnScreens, 0e) : IUnknown
 AVNCOM(IAvnClipboard, 0f) : IUnknown
 {
     virtual IAvnString* GetText () = 0;
-    virtual HRESULT SetText (char* text) = 0;
+    virtual HRESULT SetText (void* utf8Text) = 0;
     virtual HRESULT Clear() = 0;
 };
 

native/Avalonia.Native/src/OSX/Avalonia.Native.OSX.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

native/Avalonia.Native/src/OSX/clipboard.mm

@@ -16,13 +16,13 @@ public:
         }
     }
     
-    virtual HRESULT SetText (char* text) override
+    virtual HRESULT SetText (void* utf8String) override
     {
         @autoreleasepool
         {
             NSPasteboard *pasteBoard = [NSPasteboard generalPasteboard];
             [pasteBoard clearContents];
-            [pasteBoard setString:@(text) forType:NSPasteboardTypeString];
+            [pasteBoard setString:[NSString stringWithUTF8String:(const char*)utf8String] forType:NSPasteboardTypeString];
         }
         
         return S_OK;

native/Avalonia.Native/src/OSX/window.mm

@@ -530,11 +530,11 @@ private:
         }
     }
     
-    virtual HRESULT SetTitle (const char* title) override
+    virtual HRESULT SetTitle (void* utf8title) override
     {
         @autoreleasepool
         {
-            _lastTitle = [NSString stringWithUTF8String:title];
+            _lastTitle = [NSString stringWithUTF8String:(const char*)utf8title];
             [Window setTitle:_lastTitle];
             [Window setTitleVisibility:NSWindowTitleVisible];
             

src/Avalonia.Native/ClipboardImpl.cs

@@ -5,6 +5,7 @@ using System.Threading.Tasks;
 using System.Runtime.InteropServices;
 using Avalonia.Input.Platform;
 using Avalonia.Native.Interop;
+using Avalonia.Platform.Interop;
 
 namespace Avalonia.Native
 {
@@ -40,7 +41,10 @@ namespace Avalonia.Native
 
             if (text != null)
             {
-                _native.SetText(text);
+                using (var buffer = new Utf8Buffer(text))
+                {
+                    _native.SetText(buffer.DangerousGetHandle());
+                }
             }
 
             return Task.CompletedTask;

src/Avalonia.Native/WindowImpl.cs

@@ -5,6 +5,7 @@ using System;
 using Avalonia.Controls;
 using Avalonia.Native.Interop;
 using Avalonia.Platform;
+using Avalonia.Platform.Interop;
 
 namespace Avalonia.Native
 {
@@ -68,7 +69,10 @@ namespace Avalonia.Native
 
         public void SetTitle(string title)
         {
-            _native.SetTitle(title);
+            using (var buffer = new Utf8Buffer(title))
+            {
+                _native.SetTitle(buffer.DangerousGetHandle());
+            }
         }
 
         public WindowState WindowState