expo-share-extension

You can use a JavaScript file to preprocess a webpage before the share extension is activated. This is useful for extracting data like the page title or URL.

Important Constraints:

1. Enabling this option sets NSExtensionActivationSupportsWebPageWithMaxCount: 1, which is mutually exclusive with the default NSExtensionActivationSupportsWebURLWithMaxCount: 1.
2. As a result, you will no longer receive url in the initial props. To get the URL, you must extract it in your preprocessing file using window.location.href and pass it to the completionFunction.

Implementation Requirements:

• Create a class with a run(args) method.
• The run method must call args.completionFunction(data) with the results you want to pass to the extension.
• You must instantiate the class using var so it is globally accessible (e.g., var ExtensionPreprocessingJS = new ...).

class ShareExtensionPreprocessor {
  run(args) {
    args.completionFunction({
      url: window.location.href,
      title: document.title,
    });
  }
}

var ExtensionPreprocessingJS = new ShareExtensionPreprocessor();

You can customize the behavior and appearance of the share extension by passing an options object to the expo-share-extension config plugin in your app.json or app.config.(j|t)s file.

Exclude Expo Modules

To reduce the share extension's bundle size, you can manually exclude unneeded Expo modules using the excludedPackages array. Note that runtime/dev modules like expo-updates and expo-dev-client are excluded by default in newer versions, but should be manually excluded in older versions.

Custom Background Color

Set the background color using an object with red, green, blue, and alpha keys. An alpha of 0 makes the background transparent.

Custom Height

Set the height of the share extension in pixels using the height key.

React Native Firebase

Because the share extension is a separate iOS target with its own bundle ID (e.g., com.example.app.ShareExtension), you must provide a dedicated GoogleService-Info.plist via the googleServicesFile key.

[
  "expo-share-extension",
  {
    "excludedPackages": ["expo-dev-client", "expo-font"],
    "backgroundColor": {
      "red": 255,
      "green": 255,
      "blue": 255,
      "alpha": 0.8
    },
    "height": 500,
    "googleServicesFile": "./path-to-your-separate/GoogleService-Info.plist"
  }
]

Activation rules determine which content types (images, URLs, text, etc.) trigger your Share Extension in the iOS share sheet. The withShareExtensionInfoPlist plugin translates these rules into NSExtensionActivation keys in the extension's Info.plist.

Key Behaviors

• Automatic File Support: If you request image support but do not explicitly request file support, the plugin automatically adds a file rule with a max count equal to the image max count. This is done to ensure compatibility with screenshot overlays that send files instead of pure image objects.
• URL vs WebPage:
  • If you provide a preprocessingFile, the plugin enables both NSExtensionActivationSupportsWebURLWithMaxCount and NSExtensionActivationSupportsWebPageWithMaxCount.
  • If no preprocessingFile is provided, only NSExtensionActivationSupportsWebURLWithMaxCount is enabled for url type rules.
• Max Counts: For image, video, url, and file, you can specify a max property in your rule to limit how many items of that type can be shared at once.

Use the withShareExtension Config Plugin to set up the iOS Share Extension in your Expo project. This plugin handles the necessary App Group entitlements, Info.plist configurations, Podfile modifications, and Xcode target creation.

Configuration Options

Activation Rule Types

Available type values for activationRules:

• "image"
• "video"
• "text"
• "url"
• "file"

import { withShareExtension } from 'expo-share-extension';

export default ({ config }) => {
  return withShareExtension(config, {
    activationRules: [
      { type: 'image', max: 5 },
      { type: 'url' }
    ],
    backgroundColor: { red: 255, green: 255, blue: 255, alpha: 255 },
    height: 500,
    excludedPackages: ['some-heavy-package'],
    googleServicesFile: './GoogleService-Info.plist',
  });
};