Apple Targets plugin

Warning

This is highly experimental and not part of any official Expo workflow.

An experimental Expo Config Plugin that generates native Apple Targets like Widgets or App Clips, and links them outside the /ios directory. You can open Xcode and develop the targets inside the virtual expo:targets folder and the changes will be saved outside of the ios directory. This pattern enables building things that fall outside of the scope of React Native while still obtaining all the benefits of Continuous Native Generation.

🚀 How to use

• Add targets to targets/ directory with an expo-target.config.json file.
• Currently, if you don't have an Info.plist, it'll be generated on npx expo prebuild. This may be changed in the future so if you have an Info.plist it'll be used, otherwise, it'll be generated.
• Any files in a top-level target/*/assets directory will be linked as resources of the target. This was added to support Safari Extensions.
• A single top-level *.entitlements file will be linked as the entitlements of the target. This is not currently used in EAS Capability signing, but may be in the future.
• All top-level swift files will be linked as build sources of the target. There is currently no support for storyboard or .xib files because I can't be bothered.
• All top-level *.xcassets will be linked as resources, and accessible in the targets. If you add files outside of Xcode, you'll need to re-run npx expo prebuild to link them.
• Code-signing requires the teamId be provided to the plugin in app.config.js.

{
  "plugins": [
    [
      "@bacons/apple-targets",
      {
        "appleTeamId": "XXXXXXXXXX"
      }
    ]
  ]
}

You can change the root directory from ./targets to something else with root: "./src/targets". Avoid doing this.

Using React Native in Targets

I'm not sure, that's not the purpose of this plugin. I built this so I could easily build iOS widgets and other minor targets with SwiftUI. I imagine it would be straightforward to use React Native in share, notification, iMessage, Safari, and photo editing extensions, you can build that on top of this plugin if you want.

expo-target.config.json

This file can have the following properties:

{
  "type": "widget",

  // Name of the target/product. Defaults to the directory name.
  "name": "My Widget",

  // Generates colorset files for the target.
  "colors": {
    // or "$accent": "red",
    "$accent": { "color": "red", "darkColor": "blue" }
  },
  "icon": "../assets/icon.png",
  // Can also be a URL
  "frameworks": [
    // Frameworks without the extension, these will be added to the target.
    "SwiftUI"
  ],
  "entitlements": {
    // Serialized entitlements. Useful for configuring with environment variables.
  },
  // Generates xcassets for the target.
  "images": {
    "thing": "../assets/thing.png"
  },

  // The iOS version fot the target.
  "deploymentTarget": "13.4"
}

You can also use .js with the typedoc for autocomplete:

/** @type {import('@bacons/apple-targets').Config} */
module.exports = {
  type: "watch",
  colors: {
    $accent: "steelblue",
  },
  deploymentTarget: "9.4",
};

Colors

There are certain values that are shared across targets. We use a predefined convention to map these values across targets.

Name	Build Setting	Purpose
$accent	ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME	Sets the global accent color, in widgets this is used for the tint color of buttons when editing the widget.
$widgetBackground	ASSETCATALOG_COMPILER_WIDGET_BACKGROUND_COLOR_NAME	Sets the background color of the widget.

Examples

widget

I wrote a blog about this one and used it in production. Learn more: Expo x Apple Widgets.

/** @type {import('@bacons/apple-targets').Config} */
module.exports = {
  type: "widget",
  icon: "../../icons/widget.png",
  colors: {
    // This color is referenced in the Info.plist
    $widgetBackground: "#DB739C",

    $accent: "#F09458",

    // Optional: Add colors that can be used in SwiftUI.
    gradient1: {
      light: "#E4975D",
      dark: "#3E72A0",
    },
  },
  // Optional: Add images that can be used in SwiftUI.
  images: {
    valleys: "../../valleys.png",
  },
  // Optional: Add entitlements to the target, this one can be used to share data between the widget and the app.
  entitlements: {
    "com.apple.security.application-groups": ["group.bacon.data"],
  },
};

action

These show up in the share sheet. The icon should be transparent as it will be masked by the system.

/** @type {import('@bacons/apple-targets').Config} */
module.exports = {
  type: "action",
  name: "Inspect Element",
  icon: "./assets/icon.png",
  colors: {
    TouchBarBezel: "#DB739C",
  },
};

Add a JavaScript file to assets/index.js:

class Action {
  /**
   * `extensionName: "com.bacon.2095.axun"`
   * @param {*} arguments: {completionFunction: () => unknown; extensionName: string; }
   */
  run({ extensionName, completionFunction }) {
    // Here, you can run code that modifies the document and/or prepares
    // things to pass to your action's native code.

    // We will not modify anything, but will pass the body's background
    // style to the native code.
    completionFunction({
      /* */
    });
  }

  finalize() {
    // Runs after the native action code has completed.
  }
}

window.ExtensionPreprocessingJS = new Action();

Ensure NSExtensionJavaScriptPreprocessingFile: "index" in the Info.plist.

spotlight

Populate the Spotlight search results with your app's content.

/** @type {import('@bacons/apple-targets').Config} */
module.exports = {
  type: "spotlight",
};

Supported types

Ideally, this would be generated automatically based on a fully qualified Xcode project, but for now it's a manual process. The currently supported types are based on static analysis of the most commonly used targets in the iOS App Store. I haven't tested all of these and they may not work.

Type	Description
action	Share Action
widget	Widget / Live Activity
watch	Watch App (with companion iOS App)
clip	App Clip
safari	Safari Extension
share	Share Extension
notification-content	Notification Content Extension
notification-service	Notification Service Extension
intent	Siri Intent Extension
intent-ui	Siri Intent UI Extension
spotlight	Spotlight Index Extension
bg-download	Background Download Extension
quicklook-thumbnail	Quick Look Thumbnail Extension
location-push	Location Push Service Extension
credentials-provider	Credentials Provider Extension
account-auth	Account Authentication Extension

Code Signing

The codesigning is theoretically handled entirely by EAS Build. This plugin will add the requisite entitlements for target signing to work. I've only tested this end-to-end with my Pillar Valley Widget.

You can also manually sign all sub-targets if you want, I'll light a candle for you.

Xcode parsing

This plugin makes use of my proprietary Xcode parsing library, @bacons/xcode. It's mostly typed, very untested, and possibly full of bugs––however, it's still 10x nicer than the alternative.