Can I write/read data in application directory in flutter iOS?

Question

1. Is there anything else on iOS like getExternalStorageDirectory() ?

2. Is it getApplicationDocumentsDirectory() ?

3. If so, can the user access it?

4. The files in getApplicationDocumentsDirectory() can be shown as a list in the flutter iOS app?

Answer 1

use the path package, supported on all main os

https://pub.dev/packages/path

Answer 2

Unfortunately, you cannot access other app directories except for yours in iOS because of sandboxing. You can read it here as well:

https://developer.apple.com/documentation/uikit/view_controllers/providing_access_to_directories

By the way, there is a way to get other directories using swift as provided in the documentation, but I did not see any solution for it using flutter.

Hope it helps you.

Answer 3

If I'm not mistaken, you are trying to get another application directory in iOS using flutter.

There is a way to do so.

At first, let me mention that you do not need any permission for writing & reading data in iOS. It is given by default. But, the problem is getting their path. As others already mentioned that, iOS uses sandboxing, you cannot directly get access to all files and folders excluding shared storage.

Steps you need to do for reading and writing directories of other apps.

1. Install file_picker package. Link: https://pub.dev/packages/file_picker

2. Using it, popup system directory picker:

   String? selectedDirectory = await FilePicker.platform.getDirectoryPath();

PS: Users should know which folder they need to get an access. 3. When they select the folder, get the folder path and use it as you want. But there is still one thing to complete. You need to use a little bit Swift code for getting access it.

import UIKit
import Flutter
import Photos

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
      
      let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
          let batteryChannel = FlutterMethodChannel(name: "example.startAccessingToSharedStorage",
                                                    binaryMessenger: controller.binaryMessenger)
      batteryChannel.setMethodCallHandler({
        [weak self] (call: FlutterMethodCall, result: FlutterResult) -> Void in
        // This method is invoked on the UI thread.
        guard call.method == "startAccessingToSharedStorage" else {
          result(FlutterMethodNotImplemented)
          return
        }

        print("\(call.arguments)")

        self?.startAccessingToSharedStorage(result: result, call: call)
      })
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  private func startAccessingToSharedStorage(result: FlutterResult, call: FlutterMethodCall) {
    let args = call.arguments as? Dictionary<String, Any>
    if(args != nil){
       let fileUrl = URL(fileURLWithPath: (args!["url"] as? String) ?? "")
    // Get bookmark data from the provided URL
    let bookmarkData = try? fileUrl.bookmarkData()
    if let data = bookmarkData {
        // Save data
    } else {
      result("Some bad thing happened")
    }


    // Access to an external document by the bookmark data
    if let data = bookmarkData {
        var stale = false
        if let url = try? URL(resolvingBookmarkData: data, bookmarkDataIsStale: &stale),
          stale == false,
          url.startAccessingSecurityScopedResource()
        {
            var error: NSError?
            NSFileCoordinator().coordinate(readingItemAt: url, error: &error) { readURL in
                if let data = try? Data(contentsOf: readURL) {
                  result("Error occured while getting access")
                }
            }
             result("\(url.startAccessingSecurityScopedResource())\(args!["url"])")
        }
    }
    } else {result("\(args!["url"])")}
  }
}

4. Use method channel for using this function in flutter.

Answer 4

Yes, on iOS in order to get path set import:

import 'package:path_provider/path_provider.dart' as syspath;

then use:

final appDir = await syspath
          .getApplicationDocumentsDirectory();

if you save the path, keep in mind that on iOS the path changes every time we run the application.