chore(demo): conditionally add iOS target on macOS only

Author: fadi-george

.github/workflows/e2e.yml

@@ -45,6 +45,10 @@ jobs:
         with:
           dotnet-version: '10.0.x'
 
+      # Only maui-android is installable on Linux; maui-ios fails with
+      # "Workload ID maui-ios isn't supported on this platform". The iOS TFM
+      # is gated on macOS in OneSignalSDK.DotNet.csproj and demo.csproj, so
+      # restore won't try to walk it here.
       - name: Install MAUI Android workload
         run: dotnet workload install maui-android
 
@@ -103,8 +107,13 @@ jobs:
         with:
           dotnet-version: '10.0.x'
 
-      - name: Install MAUI iOS workload
-        run: dotnet workload install maui-ios
+      # Both workloads are required even though only the iOS TFM is built,
+      # because NuGet restore walks every declared TargetFramework of the
+      # multi-targeted OneSignalSDK.DotNet.csproj, and its android TFM
+      # follows references into the android-only OneSignalSDK.DotNet.Android*
+      # projects which need the android workload.
+      - name: Install MAUI workloads
+        run: dotnet workload install maui-android maui-ios
 
       - name: Create demo .env
         working-directory: examples/demo

OneSignalSDK.DotNet/OneSignalSDK.DotNet.csproj

@@ -1,6 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net10.0;net10.0-android;net10.0-ios;netstandard2.0</TargetFrameworks>
+    <!--
+      iOS TFM only on macOS hosts. NuGet restore walks every declared
+      TargetFramework of every transitively referenced project, and the iOS
+      TFM pulls in OneSignalSDK.DotNet.iOS{,.Binding}.csproj which require
+      the iOS workload. The iOS workload (`maui-ios`) cannot be installed on
+      Linux ("Workload ID maui-ios isn't supported on this platform"), so
+      consumers on Linux/Windows that only build the android TFM would
+      otherwise fail at restore with NETSDK1178 looking for Microsoft.iOS.Sdk.
+      NuGet packing for release runs on macOS, so the published package still
+      ships all four TFMs.
+    -->
+    <TargetFrameworks>net10.0;net10.0-android;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('OSX'))">$(TargetFrameworks);net10.0-ios</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <LangVersion>10.0</LangVersion>

examples/demo/demo.csproj

@@ -1,6 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net10.0-android;net10.0-ios</TargetFrameworks>
+    <!--
+      iOS targets only on macOS hosts. Linux/Windows CI runners (e.g. the
+      Android build job) don't have the iOS workload installed, and NuGet
+      restore evaluates every declared TargetFramework, which would otherwise
+      pull in NotificationServiceExtension.csproj (net10.0-ios) and fail with
+      NETSDK1178 looking for Microsoft.iOS.Sdk.
+    -->
+    <TargetFrameworks>net10.0-android</TargetFrameworks>
+    <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('OSX'))">$(TargetFrameworks);net10.0-ios</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <RootNamespace>OneSignalDemo</RootNamespace>
     <UseMaui>true</UseMaui>