React-native: How to copy file from ios project folder?

I have files in assets folder which is created in Xcode under my_project/assets. I can normally access file in my template WebView with:

source={uri:'ICF-Package/ICFPackage/index.html'}

but I can't copy this file to LibraryDirectoryPath with react-native-fs:

RNFS.copyFile('.ICF-Package/ICFPackage/index.html', RNFS.LibraryaDirectory + '/index.html').then((result) => console.log('DONE')).catch((error) => console.log(error, 'ERROR'));

Please help me with this.