Capacitor 4 download file IOS

Hi everyone,
I’m developing my App for Android and IOS and I need help for downloading files:
following my working methods for download and open files in Android, how can I fix it for IOS?
Thank you!

getDropboxFile(dropboxFileId, dropboxFileIdRootAnnex) {
  const self = this;
  axios({
    url: process.env.VUE_APP_ROOT_API + 'renplus/getDropboxFileBase64/' +
      dropboxFileId +
      '/' +
      (dropboxFileIdRootAnnex != null ? dropboxFileIdRootAnnex : '-'),
    method: 'get',
    showInCatch: 'true',
    headers: {
      Authorization: self.$store.state.token,
    },
  })
  .then(async function(response) {
    let data = response.data.renFile.fileBase64;
    let fileName = response.data.renFile.fileName;
    let res = await self.writeRenFile(fileName,data);
    self.openFile(res, fileName);
  })
  .catch(function(error) {
  });
},

async writeRenFile(fileName,data) {
  try{
   
    return await Filesystem.writeFile({
      path: fileName,
      data: data,
      directory: Directory.Data,
      // encoding: Encoding.UTF8,
      recursive: false
    });
  }catch(e){
  }
},

async openFile(res, fileName) {
    let uri = '/data/user/0/myApp/files/';
    
    let fOpts = {
      filePath: uri+fileName,
      openWithDefault: true
    }
    
    FileOpener.open(fOpts);
},

async createBase64(data) {
    let reader = new FileReader();
    reader.readAsDataURL(data);
    return reader;
},

async getUri(fileName) {
  try {
    return await Filesystem.getUri({
      path: fileName,
      directory: Directory.Data,
    });

  } catch (e) {
  }
},