tsacdop-podcast-app-android/ios/Runner/AppDelegate.swift

import UIKit
import Flutter
import flutter_downloader

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    FlutterDownloaderPlugin.setPluginRegistrantCallback(registerPlugins)
    UIApplication.shared.setMinimumBackgroundFetchInterval(TimeInterval(60*60*4))
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

private func registerPlugins(registry: FlutterPluginRegistry) { 
    if (!registry.hasPlugin("FlutterDownloaderPlugin")) {
       FlutterDownloaderPlugin.register(with: registry.registrar(forPlugin: "FlutterDownloaderPlugin"))
    }
}