virgool-blog-0002

flatMap.swift

struct PostAndComments {
    var post: Post
    var comments: [Comment]
}

func showPostsWithComments() -> Future<[PostAndComments]> {
    return getPostsFromDatabase().flatMap { posts -> Future<[PostAndComments]> in    
        return posts.flatMap { post -> Future<[PostAndComments]> in
            return post.getComments().map { comments -> [PostAndComments] in
                  return PostAndComment(post: post, comments: comments)         
            }
         }
      }
}