Define RESOURCES_UI_FRAMEWORK_FAMILY in the xcspec

Presently this value is taken from SDKSettings. Define it closer to the build setting itself so that it's more obvious how this is used.

Author: jakepetroules

Sources/SWBApplePlatform/Specs/AssetCatalogCompiler.xcspec

@@ -284,7 +284,8 @@
             {
                 Name = "RESOURCES_UI_FRAMEWORK_FAMILY";
                 Type = String;
-                CommandLineFlag = "--ui-framework-family";
+                Condition = "$(IS_MACCATALYST)";
+                CommandLineArgs = ("--ui-framework-family", "uikit");
             },
 
             // COMPRESS_PNG_FILES is defined by CopyPNGFile.xcspec

Tests/SWBTaskConstructionTests/AssetCatalogTaskConstructionTests.swift

@@ -577,6 +577,60 @@ fileprivate struct AssetCatalogTaskConstructionTests: CoreBasedTests {
         }
     }
 
+    /// `--ui-framework-family uikit` should be passed to actool when (and only when) building for
+    /// Mac Catalyst.
+    @Test(.requireSDKs(.macOS, .iOS))
+    func uiFrameworkFamilyForMacCatalyst() async throws {
+        let actoolPath = try await self.actoolPath
+        try await withTemporaryDirectory { tmpDir in
+            let testProject = TestProject(
+                "aProject",
+                sourceRoot: tmpDir,
+                groupTree: TestGroup("Root", children: [
+                    TestFile("Assets.xcassets"),
+                ]),
+                buildConfigurations: [
+                    TestBuildConfiguration("Debug", buildSettings: [
+                        "ASSETCATALOG_EXEC": actoolPath.str,
+                        "AD_HOC_CODE_SIGNING_ALLOWED": "YES",
+                        "CODE_SIGN_IDENTITY": "-",
+                        "GENERATE_INFOPLIST_FILE": "YES",
+                        "PRODUCT_NAME": "$(TARGET_NAME)",
+                        "SDKROOT": "iphoneos",
+                        "SUPPORTS_MACCATALYST": "YES",
+                        "TARGETED_DEVICE_FAMILY": "2,6",
+                    ])
+                ],
+                targets: [
+                    TestStandardTarget(
+                        "App",
+                        type: .framework,
+                        buildPhases: [
+                            TestResourcesBuildPhase(["Assets.xcassets"]),
+                        ])
+                ]
+            )
+
+            let tester = try await TaskConstructionTester(getCore(), testProject)
+
+            // When building for Mac Catalyst, --ui-framework-family uikit should be emitted.
+            await tester.checkBuild(runDestination: .macCatalyst) { results in
+                results.checkTask(.matchRuleType("CompileAssetCatalogVariant"), .matchRuleItem("thinned")) { task in
+                    task.checkCommandLineContainsUninterrupted(["--ui-framework-family", "uikit"])
+                }
+                results.checkNoDiagnostics()
+            }
+
+            // When building for iOS device (not Mac Catalyst), the flag should NOT be emitted.
+            await tester.checkBuild(runDestination: .iOS) { results in
+                results.checkTask(.matchRuleType("CompileAssetCatalogVariant"), .matchRuleItem("thinned")) { task in
+                    task.checkCommandLineDoesNotContain("--ui-framework-family")
+                }
+                results.checkNoDiagnostics()
+            }
+        }
+    }
+
     /// When asset symbol generation is disabled, the asset catalog must stay in the Resources phase
     /// and not be moved to Sources. This matters for projects where the xcassets is generated by a
     /// preceding script phase and doesn't exist during Sources processing.