Fix example build on flutter mac

Author: liamappelbe

.github/workflows/objective_c.yaml

@@ -94,8 +94,10 @@ jobs:
           channel: stable
       - name: Install dependencies
         run: flutter pub get
-      - name: Build the example app
+      - name: Build the example app for macos
         run: flutter build macos
+      - name: Build the example app for ios
+        run: flutter build ios
       - name: Check for xcode for analyzer warnings
         run: xcodebuild analyze -workspace macos/Runner.xcworkspace -scheme Runner -configuration Debug GCC_TREAT_WARNINGS_AS_ERRORS=YES
 

pkgs/objective_c/hook/build.dart

@@ -12,7 +12,6 @@ import 'package:native_toolchain_c/src/cbuilder/compiler_resolver.dart';
 const objCFlags = ['-x', 'objective-c', '-fobjc-arc'];
 
 String sdkPath = firstLineOfStdout('xcrun', ['--show-sdk-path']);
-final cFlags = <String>['-isysroot', sdkPath];
 
 const assetName = 'objective_c.dylib';
 
@@ -29,7 +28,8 @@ final logger = Logger('')
 void main(List<String> args) async {
   await build(args, (input, output) async {
     const supportedOSs = {OS.iOS, OS.macOS};
-    if (!supportedOSs.contains(input.config.code.targetOS)) {
+    final os = input.config.code.targetOS;
+    if (!supportedOSs.contains(os)) {
       // Nothing to do.
       return;
     }
@@ -42,6 +42,9 @@ void main(List<String> args) async {
     final assetPath = input.outputDirectory.resolve(assetName);
     final srcDir = Directory.fromUri(input.packageRoot.resolve('src/'));
 
+    final arch = input.config.code.targetArchitecture;
+    final target = '${clangArchName(arch)}-apple-${os.name}';
+
     final cFiles = <String>[];
     final mFiles = <String>[];
     final hFiles = <String>[];
@@ -56,15 +59,17 @@ void main(List<String> args) async {
 
     cFiles.addAll(extraCFiles.map((f) => input.packageRoot.resolve(f).path));
 
+    final cFlags = <String>['-isysroot', sdkPath, '-target', target];
     final mFlags = [...cFlags, ...objCFlags];
+    final linkFlags = cFlags;
 
     final builder = await Builder.create(input, input.packageRoot.path);
 
     final objectFiles = await Future.wait(<Future<String>>[
       for (final src in cFiles) builder.buildObject(src, cFlags),
       for (final src in mFiles) builder.buildObject(src, mFlags),
     ]);
-    await builder.linkLib(objectFiles, assetPath.toFilePath());
+    await builder.linkLib(objectFiles, assetPath.toFilePath(), linkFlags);
 
     output.dependencies.addAll(cFiles.map(Uri.file));
     output.dependencies.addAll(mFiles.map(Uri.file));
@@ -108,11 +113,15 @@ class Builder {
     return output;
   }
 
-  Future<void> linkLib(List<String> objects, String output) => _compile([
+  Future<void> linkLib(
+    List<String> objects,
+    String output,
+    List<String> flags,
+  ) => _compile([
     '-shared',
     '-undefined',
     'dynamic_lookup',
-    ...cFlags,
+    ...flags,
     ...objects,
   ], output);
 
@@ -138,3 +147,6 @@ String firstLineOfStdout(String cmd, List<String> args) {
       .where((line) => line.isNotEmpty)
       .first;
 }
+
+String clangArchName(Architecture arch) =>
+    arch == Architecture.x64 ? 'x86_64' : arch.name;