The argument type 'List<String>' can't be assigned to the parameter type '-CodePudding

I've been learning flutter for 2 months. I'm trying to develop a wallpaper app. I created a model and a function. But right now I can only download 1 wallpaper. How can I make this a list? I get this error when I make a list.

This is url.

  String url =
      'https://images.hdqwalls.com/download/the-witcher-season-2-2022-5k-u1-1080x1920.jpg';

the list i want to use

  List<String> url = [
    'https://images.hdqwalls.com/download/the-witcher-season-2-2022-5k-u1-1080x1920.jpg',
    'https://images.hdqwalls.com/download/the-witcher-season-2-2022-5k-u1-1080x1920.jpg',
  ];

and function

  void saveimage() async {
    await GallerySaver.saveImage(url, albumName: album_name);
  }

and clicking this button provides download

 ElevatedButton DownloadButton(BuildContext context) {
    return ElevatedButton(
      style: ElevatedButton.styleFrom(
        minimumSize: Size(40, 40),
        shape: CircleBorder(),
        backgroundColor: Colors.grey.shade600.withOpacity(0.1),
      ),
      child: Icon(Icons.download, color: Colors.white.withOpacity(0.7)),
      onPressed: () {
        saveimage();
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            duration: Duration(seconds: 2),
            content: Text('Wallpaper downloaded!'),
            action: SnackBarAction(
              label: '',
              onPressed: () {},
            ),
          ),
        );
      },
    );
  }

Problem image

The packages I use are

gallery_saver: ^2.3.2
async_wallpaper: ^2.0.1

I want to use it in gridview

GridView.builder(
        itemCount: url.length,
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 2,
          childAspectRatio: 9 / 16,
        ),
        itemBuilder: (BuildContext context, int index) {
          return Card(
            child: Padding(
              padding: EdgeInsets.all(1.0),
              child: FullScreenWidget(
                child: Stack(fit: StackFit.expand, children: [
                  Image.network(url, fit: BoxFit.cover),

CodePudding user response：

    void saveimage() async {
       for(int i = 0; i <= url.length; i  ) {
            await GallerySaver.saveImage(url[I], albumName: album_name);
         }
      }

Above code will resolve your error

CodePudding user response：

Let consider you want to download image when you click on the card then code will be like as following.

void saveimage(String imageUrl) async {
    await GallerySaver.saveImage(imageUrl, albumName: album_name);
  }

GridView.builder(
  itemCount: url.length,
  gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
  crossAxisCount: 2,
  childAspectRatio: 9 / 16,
  ),
  itemBuilder: (BuildContext context, int index) {
  return GestureDetector(
  onTap: (){
    await saveimage(url[index]);
  },
    child: Card(
    child: Padding(
    padding: EdgeInsets.all(1.0),
    child: FullScreenWidget(
    child: Stack(fit: StackFit.expand, children: [
    Image.network(url, fit: BoxFit.cover),]),),);),
  ),)