Move Environment.iOS.cs under libraries

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -2242,7 +2242,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.FreeBSD.cs" Condition="'$(TargetsFreeBSD)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Linux.cs" Condition="'$(TargetsLinux)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.OSX.cs" Condition="'$(TargetsOSX)' == 'true' or '$(TargetsMacCatalyst)' == 'true'" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Environment.iOS.cs" Condition="'$(TargetsiOS)' == 'true' or '$(TargetstvOS)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Environment.iOS.cs" Condition="'$(IsiOSLike)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.OSVersion.Unix.cs" Condition="'$(IsOSXLike)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.SunOS.cs" Condition="'$(Targetsillumos)' == 'true' or '$(TargetsSolaris)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\TimeZoneInfo.FullGlobalizationData.Unix.cs" Condition="'$(UseMinimalGlobalizationData)' != 'true'" />
@@ -2274,6 +2274,14 @@
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStatus.SetTimes.OSX.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(IsiOSLike)' == 'true'">
+    <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.SearchPath.cs">
+      <Link>Common\Interop\OSX\Interop.SearchPath.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.SearchPathTempDirectory.cs">
+      <Link>Common\Interop\OSX\Interop.SearchPathTempDirectory.cs</Link>
+    </Compile>
+  </ItemGroup>
   <ItemGroup Condition="'$(TargetsMacCatalyst)' == 'true'">
     <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.iOSSupportVersion.cs" Link="Common\Interop\OSX\System.Native\Interop.iOSSupportVersion.cs" />
   </ItemGroup>

src/libraries/System.Private.CoreLib/src/System/Environment.iOS.cs

@@ -1,13 +1,124 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.IO;
+using System.Threading;
+using System.Collections.Generic;
 using System.Runtime.InteropServices;
+using NSSearchPathDirectory = Interop.Sys.NSSearchPathDirectory;
 
 namespace System
 {
     public static partial class Environment
     {
+#if !TARGET_MACCATALYST
         // iOS/tvOS aren't allowed to call libproc APIs so return 0 here, this also matches what we returned in earlier releases
         public static long WorkingSet => 0;
+#endif
+
+        private static Dictionary<SpecialFolder, string>? s_specialFolders;
+
+        private static string GetFolderPathCore(SpecialFolder folder, SpecialFolderOption option)
+        {
+            if (s_specialFolders == null)
+            {
+                Interlocked.CompareExchange(ref s_specialFolders, new Dictionary<SpecialFolder, string>(), null);
+            }
+
+            string? path;
+            lock (s_specialFolders)
+            {
+                if (!s_specialFolders.TryGetValue(folder, out path))
+                {
+                    path = GetSpecialFolder(folder) ?? string.Empty;
+                    s_specialFolders[folder] = path;
+                }
+            }
+            return path;
+        }
+
+        private static string? GetSpecialFolder(SpecialFolder folder)
+        {
+            switch (folder)
+            {
+                case SpecialFolder.Personal:
+                case SpecialFolder.LocalApplicationData:
+                    return CombineDocumentDirectory(string.Empty);
+
+                case SpecialFolder.ApplicationData:
+                    // note: at first glance that looked like a good place to return NSLibraryDirectory
+                    // but it would break isolated storage for existing applications
+                    return CombineDocumentDirectory(".config");
+
+                case SpecialFolder.Resources:
+                    return Interop.Sys.SearchPath(NSSearchPathDirectory.NSLibraryDirectory); // older (8.2 and previous) would return String.Empty
+
+                case SpecialFolder.Desktop:
+                case SpecialFolder.DesktopDirectory:
+                    return Path.Combine(GetFolderPathCore(SpecialFolder.Personal, SpecialFolderOption.None), "Desktop");
+
+                case SpecialFolder.MyMusic:
+                    return Path.Combine(GetFolderPathCore(SpecialFolder.Personal, SpecialFolderOption.None), "Music");
+
+                case SpecialFolder.MyPictures:
+                    return Path.Combine(GetFolderPathCore(SpecialFolder.Personal, SpecialFolderOption.None), "Pictures");
+
+                case SpecialFolder.Templates:
+                    return CombineDocumentDirectory("Templates");
+
+                case SpecialFolder.MyVideos:
+                    return Path.Combine(GetFolderPathCore(SpecialFolder.Personal, SpecialFolderOption.None), "Videos");
+
+                case SpecialFolder.CommonTemplates:
+                    return "/usr/share/templates";
+
+                case SpecialFolder.Fonts:
+                    return CombineDocumentDirectory(".fonts");
+
+                case SpecialFolder.Favorites:
+                    return CombineSearchPath(NSSearchPathDirectory.NSLibraryDirectory, "Favorites");
+
+                case SpecialFolder.ProgramFiles:
+                    return Interop.Sys.SearchPath(NSSearchPathDirectory.NSApplicationDirectory);
+
+                case SpecialFolder.InternetCache:
+                    return Interop.Sys.SearchPath(NSSearchPathDirectory.NSCachesDirectory);
+
+                case SpecialFolder.UserProfile:
+                    return GetEnvironmentVariable("HOME");
+
+                case SpecialFolder.CommonApplicationData:
+                    return "/usr/share";
+
+                default:
+                    return string.Empty;
+            }
+
+            static string CombineSearchPath(NSSearchPathDirectory searchPath, string subdirectory)
+            {
+                string? path = Interop.Sys.SearchPath(searchPath);
+                return path != null ?
+                    Path.Combine(path, subdirectory) :
+                    string.Empty;
+            }
+
+            static string CombineDocumentDirectory(string subdirectory)
+            {
+#if TARGET_TVOS
+                string? path = CombineSearchPath(NSSearchPathDirectory.NSLibraryDirectory, Path.Combine("Caches", "Documents"));
+                // Special version of CombineSearchPath which creates the path if needed.
+                // This isn't needed for "real" search paths which always exist, but on tvOS
+                // the base path is really a subdirectory we define rather than an OS directory.
+                // In order to not treat Directory.Exists(SpecialFolder.ApplicationData) differently
+                // on tvOS, guarantee that it exists by creating it here
+                if (!Directory.Exists(path))
+                    Directory.CreateDirectory(path);
+                path = Path.Combine(path, subdirectory);
+#else
+                string? path = CombineSearchPath(NSSearchPathDirectory.NSDocumentDirectory, subdirectory);
+#endif
+                return path;
+            }
+        }
     }
 }

src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -279,15 +279,6 @@
         <Link>Common\Interop\Unix\System.Native\Interop.GetEnviron.cs</Link>
       </Compile>
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetsMacCatalyst)' == 'true' or '$(TargetsiOS)' == 'true' or '$(TargetstvOS)' == 'true'">
-      <Compile Include="$(BclSourcesRoot)\System\Environment.iOS.cs" />
-      <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.SearchPath.cs">
-        <Link>Common\Interop\OSX\Interop.SearchPath.cs</Link>
-      </Compile>
-      <Compile Include="$(CommonPath)Interop\OSX\System.Native\Interop.SearchPath.iOS.cs">
-        <Link>Common\Interop\OSX\Interop.SearchPath.iOS.cs</Link>
-      </Compile>
-  </ItemGroup>
   <ItemGroup Condition="'$(TargetsBrowser)' == 'true'">
       <Compile Include="$(BclSourcesRoot)\System\Threading\TimerQueue.Browser.Mono.cs" />
   </ItemGroup>