Change your return type like this Task<List<photos>>
public async Task<List<photos>> GetList()
{
List<Photos> photos = new List<Photos>();
if (photoIds != null)
{
foreach (int photoId in photoIds)
{
Photo photo = await ImageRepository.GetAsync(photoId);
if (photo != null)
photos.Add(photo);
}
}
return photos;
}
To call
var list = await GetList()