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Voice download

Last updated: July 15, 2026 | 2 minutes read

In this guide, you will learn how to list the voice downloads available on the server, how to download a voice, and track the download progress.

How it works​

The example app demonstrates the following features:

  • Get a list of available voices
  • Download a voice
Initial map screen
Downloaded multiple voices

Initialize the Map​

This callback function is called when the interactive map is initialized and ready to use. Allows mobile data usage for content downloads.


  void _onMapCreated(GemMapController controller) async {
    SdkSettings.setAllowOffboardServiceOnExtraChargedNetwork(
      ServiceGroupType.contentService,
      true,
    );
  }

Navigate to Voices Page​

A tap on the voice icon in the app bar calls this method to navigate to the voice download screen.


  // Method to navigate to the Voices Page.
  void _onVoicesButtonTap(BuildContext context) async {
    Navigator.of(context).push(
      MaterialPageRoute<dynamic>(builder: (context) => const VoicesPage()),
    );
  }

Retrieve List of Voices​

The list of voices available for download is obtained from the server using ContentStore.asyncGetStoreContentList(ContentType.voice).

voices_page.dartView on Github
  Future<List<ContentStoreItem>> _getVoices() {
    Completer<List<ContentStoreItem>> voicesList =
        Completer<List<ContentStoreItem>>();
    ContentStore.asyncGetStoreContentList(ContentType.humanVoice, (
      err,
      items,
      isCached,
    ) {
      if (err == GemError.success && items.isNotEmpty) {
        voicesList.complete(items);
      }
    });
    return voicesList.future;
  }

Display Voices​

The voices are displayed in a list, and a CircularProgressIndicator is shown while the voices are being loaded.

voices_page.dartView on Github
      body: FutureBuilder<List<ContentStoreItem>>(
        future: _getVoices(),
        builder: (context, snapshot) {
          if (!snapshot.hasData || snapshot.data == null) {
            return const Center(child: CircularProgressIndicator());
          }
          return Scrollbar(
            child: ListView.separated(
              padding: EdgeInsets.zero,
              itemCount: snapshot.data!.length,
              separatorBuilder: (context, index) =>
                  const Divider(indent: 50, height: 0),
              itemBuilder: (context, index) {
                final voice = snapshot.data!.elementAt(index);
                return VoicesItem(voice: voice);
              },
            ),
          );
        },

Download Voice​

This method initiates the voice download.

voices_item.dartView on Github

  void _downloadVoice() {
    // Download the voice.
    widget.voice.asyncDownload(
      _onVoiceDownloadFinished,
      onProgress: _onVoiceDownloadProgressUpdated,
      allowChargedNetworks: true,
    );
  }

Retrieve Country Flag​

This method retrieves the flag image for each voice.

voices_item.dartView on Github
  Img? _getCountryImage(ContentStoreItem voice) {
    final countryCodes = voice.countryCodes;
    final countryImage = MapDetails.getCountryFlagImg(countryCodes[0]);
    return countryImage;
  }
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