feat(cli): support SPM package traits in generated Package.swift

cli/src/declarations.ts

@@ -507,6 +507,21 @@ export interface CapacitorConfig {
        */
       provisioningProfile?: string;
     };
+
+    spm?: {
+      /**
+       * Define package traits for SPM plugin dependencies.
+       *
+       * The key is the plugin ID (e.g. `@capacitor-firebase/analytics`)
+       * and the value is an array of trait names.
+       *
+       * Packages can have default traits. If you use this property, and
+       * want to preserve the defaults, include ".defaults" in the array.
+       *
+       * @since 8.2.0
+       */
+      packageTraits?: { [pluginId: string]: string[] };
+    };
   };
 
   server?: {

cli/src/util/spm.ts

@@ -98,8 +98,11 @@ export async function removeCocoapodsFiles(config: Config): Promise<void> {
 export async function generatePackageText(config: Config, plugins: Plugin[]): Promise<string> {
   const iosPlatformVersion = await getCapacitorPackageVersion(config, config.ios.name);
   const iosVersion = getMajoriOSVersion(config);
+  const packageTraits = config.app.extConfig.ios?.spm?.packageTraits ?? {};
+  const hasTraits = Object.keys(packageTraits).length > 0;
+  const swiftToolsVersion = hasTraits ? '6.1' : '5.9';
 
-  let packageSwiftText = `// swift-tools-version: 5.9
+  let packageSwiftText = `// swift-tools-version: ${swiftToolsVersion}
 import PackageDescription
 
 // DO NOT MODIFY THIS FILE - managed by Capacitor CLI commands
@@ -119,7 +122,16 @@ let package = Package(
       packageSwiftText += `,\n        .package(name: "${plugin.name}", path: "../../capacitor-cordova-ios-plugins/sources/${plugin.name}")`;
     } else {
       const relPath = relative(config.ios.nativeXcodeProjDirAbs, plugin.rootPath);
-      packageSwiftText += `,\n        .package(name: "${plugin.ios?.name}", path: "${relPath}")`;
+      const traits = packageTraits[plugin.id];
+      const traitsSuffix = traits?.length
+        ? `, traits: [${traits
+            .map((t) => {
+              // Any trait is written with quotes, with the exception of .defaults
+              return /^\.?defaults?$/i.test(t) ? '.defaults' : `"${t}"`;
+            })
+            .join(', ')}]`
+        : '';
+      packageSwiftText += `,\n        .package(name: "${plugin.ios?.name}", path: "${relPath}"${traitsSuffix})`;
     }
   }