モバイルデバイス機能の追加

Our photo gallery app won’t be complete until it runs on iOS, Android, and the web - all using one codebase. All it takes is some small logic changes to support mobile platforms, installing some native tooling, then running the app on a device. Let’s go!

Let’s start with making some small code changes - then our app will “just work” when we deploy it to a device.

Platform-specific Logic

First, we’ll update the photo saving functionality to support mobile. In the savePicture function, check which platform the app is running on. If it’s “hybrid” (Capacitor or Cordova, the two native runtimes), then read the photo file into base64 format using the readFile method. Also, return the complete file path to the photo using the Filesystem API. When setting the webviewPath, use the special Capacitor.convertFileSrc method (details here). Otherwise, use the same logic as before when running the app on the web.

const savePicture = async (photo: Photo, fileName: string): Promise<UserPhoto> => {
  let base64Data: string;
  // "hybrid" will detect Cordova or Capacitor;
  if (isPlatform('hybrid')) {
    const file = await Filesystem.readFile({
      path: photo.path!,
    });
    base64Data = file.data;
  } else {
    base64Data = await base64FromPath(photo.webPath!);
  }
  const savedFile = await Filesystem.writeFile({
    path: fileName,
    data: base64Data,
    directory: Directory.Data,
  });

  if (isPlatform('hybrid')) {
    // Display the new image by rewriting the 'file://' path to HTTP
    // Details: https://ionicframework.com/docs/building/webview#file-protocol
    return {
      filepath: savedFile.uri,
      webviewPath: Capacitor.convertFileSrc(savedFile.uri),
    };
  } else {
    // Use webPath to display the new image instead of base64 since it's
    // already loaded into memory
    return {
      filepath: fileName,
      webviewPath: photo.webPath,
    };
  }
};

Next, add a new bit of logic in the loadSaved function. On mobile, we can directly point to each photo file on the Filesystem and display them automatically. On the web, however, we must read each image from the Filesystem into base64 format. This is because the Filesystem API uses IndexedDB under the hood. Update the loadSaved function inside of useEffect to:

const loadSaved = async () => {
  const { value } = await Preferences.get({ key: PHOTO_STORAGE });

  const photosInPreferences = (value ? JSON.parse(value) : []) as UserPhoto[];
  // If running on the web...
  if (!isPlatform('hybrid')) {
    for (let photo of photosInPreferences) {
      const file = await Filesystem.readFile({
        path: photo.filepath,
        directory: Directory.Data,
      });
      // Web platform only: Load the photo as base64 data
      photo.webviewPath = `data:image/jpeg;base64,${file.data}`;
    }
  }
  setPhotos(photosInPreferences);
};

Our Photo Gallery now consists of one codebase that runs on the web, Android, and iOS. Next up, the part you’ve been waiting for - deploying the app to a device.