Capacitor Plugin Spm Support

Add SPM Support to a Capacitor Plugin

Add Swift Package Manager (SPM) support to an existing Capacitor plugin by replacing the Objective-C bridge with the CAPBridgedPlugin Swift protocol and adding a Package.swift manifest.

Prerequisites

The project must be a Capacitor plugin (not an app project). The plugin must have an existing iOS implementation with Swift source files in ios/Plugin/.

Procedures

Step 1: Gather Plugin Information

1. Read package.json in the plugin root. Extract:
   • The plugin package name (e.g., @capawesome/capacitor-app-review).
   • The existing files array entries.
   • The existing scripts entries.
2. Read the .podspec file in the plugin root. Extract:
   • The pod name (the Pod::Spec.new argument, e.g., CapawesomeCapacitorAppReview). This becomes the SPM package name.
   • The iOS deployment target from s.ios.deployment_target (e.g., '13.0'). Extract the major version number (e.g., 13). This becomes the SPM iOS version.
   • All third-party CocoaPods dependencies — any s.dependency or spec.dependency entries that are not Capacitor or CapacitorCordova. Record each dependency name and version constraint.
3. Identify the plugin Swift file in ios/Plugin/. It contains a class extending CAPPlugin with @objc(<PluginClassName>). Extract:
   • The plugin class name (e.g., AppReviewPlugin).
   • The JavaScript name from the Objective-C .m file's CAP_PLUGIN macro first string argument (e.g., AppReview).
   • All plugin methods from CAP_PLUGIN_METHOD macro calls in the .m file, noting each method's name and return type (e.g., CAPPluginReturnPromise).
4. Identify the Objective-C bridge files in ios/Plugin/:
   • <PluginClassName>.h (header file)
   • <PluginClassName>.m (implementation file with CAP_PLUGIN macro)
5. Read the Capacitor peer dependency version from package.json (peerDependencies["@capacitor/core"]). Determine the major version (e.g., 6). This is the Capacitor major version.

Step 2: Resolve CocoaPods Dependencies for SPM

Skip this step if no third-party CocoaPods dependencies were found in Step 1.

For each third-party CocoaPods dependency, an equivalent SPM-compatible package is needed. Present the list of dependencies to the user and ask whether they can provide the SPM package URLs themselves, or whether the agent should search the web for SPM equivalents.

If the user provides SPM package URLs: Record them and proceed to Step 3.

If the user requests a web search: For each CocoaPods dependency:

1. Search the web for "<dependency_name>" Swift Package Manager to determine whether the original CocoaPods dependency also supports SPM. Many popular libraries (e.g., Firebase, Alamofire) distribute via both CocoaPods and SPM from the same repository.
2. If the original library supports SPM, use its Git repository URL. Use the same version as specified in the podspec — convert the CocoaPods version constraint to the SPM equivalent (e.g., ~> 5.0 becomes .upToNextMajor(from: "5.0.0"), = 2.1.0 becomes .exact("2.1.0")).
3. If the original library does not support SPM, search for "<dependency_name>" SPM alternative to find a replacement package that provides equivalent functionality via SPM. Use a version that is compatible with the version used in the podspec.
4. If no SPM-compatible alternative exists, inform the user and ask how to proceed.

Record the resolved SPM package URL, version requirement, and product name(s) for each dependency. These will be added to Package.swift in the next step.

Step 3: Create Package.swift

Create Package.swift in the plugin root directory with the following content:

swiftCopy code
// swift-tools-version: 5.9
import PackageDescription

let package = Package(
    name: "<SPM_PACKAGE_NAME>",
    platforms: [.iOS(.v<SPM_IOS_VERSION>)],
    products: [
        .library(
            name: "<SPM_PACKAGE_NAME>",
            targets: ["<PLUGIN_CLASS_NAME>"])
    ],
    dependencies: [
        .package(url: "https://github.com/ionic-team/capacitor-swift-pm.git", branch: "<CAPACITOR_MAJOR_VERSION>.0.0")
        // <ADDITIONAL_PACKAGE_DEPENDENCIES>
    ],
    targets: [
        .target(
            name: "<PLUGIN_CLASS_NAME>",
            dependencies: [
                .product(name: "Capacitor", package: "capacitor-swift-pm"),
                .product(name: "Cordova", package: "capacitor-swift-pm")
                // <ADDITIONAL_TARGET_DEPENDENCIES>
            ],
            path: "ios/Plugin"),
        .testTarget(
            name: "<PLUGIN_CLASS_NAME>Tests",
            dependencies: ["<PLUGIN_CLASS_NAME>"],
            path: "ios/PluginTests")
    ]
)

Replace all placeholders:

• <SPM_IOS_VERSION> — the SPM iOS version from Step 1 (e.g., 13).
• <SPM_PACKAGE_NAME> — the pod name from Step 1 (e.g., CapawesomeCapacitorAppReview).
• <PLUGIN_CLASS_NAME> — the plugin class name from Step 1 (e.g., AppReviewPlugin).
• <CAPACITOR_MAJOR_VERSION> — the Capacitor major version from Step 1 (e.g., 6).
• <ADDITIONAL_PACKAGE_DEPENDENCIES> — if third-party dependencies were resolved in Step 2, add a .package(url: "<repo_url>", <version_requirement>) entry for each. Remove the comment line if no extra dependencies exist.
• <ADDITIONAL_TARGET_DEPENDENCIES> — for each package dependency added above, add a corresponding .product(name: "<ProductName>", package: "<package-name>") entry. Remove the comment line if no extra dependencies exist.

Step 4: Update the Swift Plugin Class

Open the plugin Swift file (e.g., ios/Plugin/<PluginClassName>.swift).

1. Add CAPBridgedPlugin protocol conformance to the class declaration.
2. Add the three required properties as the first properties in the class body, before any existing properties.

Apply this diff pattern:

diffCopy code
 @objc(<PluginClassName>)
-public class <PluginClassName>: CAPPlugin {
+public class <PluginClassName>: CAPPlugin, CAPBridgedPlugin {
+    public let identifier = "<PluginClassName>"
+    public let jsName = "<JS_NAME>"
+    public let pluginMethods: [CAPPluginMethod] = [
+        CAPPluginMethod(name: "<method1>", returnType: CAPPluginReturnPromise),
+        CAPPluginMethod(name: "<method2>", returnType: CAPPluginReturnPromise)
+    ]

Replace:

• <PluginClassName> — the plugin class name (e.g., AppReviewPlugin).
• <JS_NAME> — the JavaScript name from the .m file's CAP_PLUGIN macro (e.g., AppReview).
• The pluginMethods array — list all methods from the .m file's CAP_PLUGIN_METHOD calls, preserving each method's name and return type exactly.

Step 5: Delete Objective-C Bridge Files

Delete the following files from ios/Plugin/:

• <PluginClassName>.h
• <PluginClassName>.m

These are no longer needed because the plugin registration is now handled by the CAPBridgedPlugin protocol in Swift.

Step 6: Clean Up the Xcode Project File

Open ios/Plugin.xcodeproj/project.pbxproj and remove all references to the deleted Objective-C files. Specifically, remove lines referencing:

• <PluginClassName>.h — file references, build phase entries (PBXBuildFile, PBXFileReference, PBXGroup children, PBXHeadersBuildPhase)
• <PluginClassName>.m — file references, build phase entries (PBXBuildFile, PBXFileReference, PBXGroup children, PBXSourcesBuildPhase)

Search for both filenames in the .pbxproj file and remove every line that references them.

Step 7: Update .gitignore

Open .gitignore in the plugin root. Add the following entries if not already present:

diffCopy code
 # iOS files
+Package.resolved
+/.build
+/Packages
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

Place these entries in the iOS section of the .gitignore file, after any existing iOS-related entries (e.g., Pods, Podfile.lock).

Step 8: Update package.json

Apply two changes to package.json:

1. Add "Package.swift" to the files array:

diffCopy code
     "ios/Plugin/",
-    "<PodName>.podspec"
+    "<PodName>.podspec",
+    "Package.swift"
   ],

2. Add the ios:spm:install script to the scripts object:

diffCopy code
     "ios:pod:install": "cd ios && pod install --repo-update && cd ..",
+    "ios:spm:install": "cd ios && swift package resolve && cd ..",

If the ios:pod:install script does not exist, add the ios:spm:install script after the last existing script entry.

Step 9: Verify

1. Run npm install in the plugin root to ensure package.json is valid.
2. Verify the iOS build still succeeds by building the plugin's example or test app.

Error Handling

• If the .pbxproj file becomes corrupted after removing ObjC references, restore it from version control and carefully re-edit, ensuring only complete lines are removed.
• If the Swift build fails with CAPBridgedPlugin not found, verify that @capacitor/core is version 6+ and that capacitor-swift-pm branch matches the Capacitor major version.
• If SPM resolution fails (swift package resolve), verify the Package.swift target paths match the actual directory structure (ios/Plugin for sources, ios/PluginTests for tests).
• If the plugin has no test target directory (ios/PluginTests), remove the .testTarget block from Package.swift.
• If the plugin has additional Swift source files beyond the main plugin file, no extra changes are needed — SPM automatically includes all .swift files in the target path.
• If the .m file uses CAPPluginReturnNone instead of CAPPluginReturnPromise for some methods, preserve the original return type in the pluginMethods array.
• If a CocoaPods dependency has no SPM equivalent and no alternative can be found, the plugin cannot fully support SPM. Inform the user and suggest they either vendor the dependency source or wait for upstream SPM support.

Related Skills

• capacitor-plugin-development — For creating new Capacitor plugins from scratch, including scaffolding, native implementation, and publishing.
• capacitor-plugin-upgrades — For upgrading a Capacitor plugin to a newer major version.