swift - 无法将类型 '[Message]' 的值转换为预期的参数类型 'Message'

Question

我正在关注 this教程，我收到标题中显示的错误，这是我的代码:

func loadData()
{
    let delegate = UIApplication.shared.delegate as? AppDelegate

    if let context = delegate?.persistentContainer.viewContext
    {
        if let friends = fetchFriends()
        {
            messages = [Message]()

            for friend in friends
            {
                print(friend.name) // This line btw for some reason is giving me: Expression implicitly coerced from 'String?' to Any

                let fetchRequest:NSFetchRequest<Message> = Message.fetchRequest()
                fetchRequest.sortDescriptors = [NSSortDescriptor(key: "date", ascending: false)]
                fetchRequest.predicate = NSPredicate(format: "friend.name = %@", friend.name!)
                fetchRequest.fetchLimit = 1

                do
                {
                    let fetchedMessages = try(context.fetch(fetchRequest))
                    messages?.append(fetchedMessages)
                    // This above line is the line which is giving me this error:
                    //Cannot convert value of type '[Message]' to expected argument type 'Message'
                }
                catch let err
                {
                    print(err)
                }
            }
        }
    }
}

正如您从大约 13 分钟看到的那样，我的代码看起来并不完全相同，因为视频有点旧并且使用的是旧版本的 swift。

我希望有人能帮我解决这个错误，因为我不知道该怎么做，提前谢谢你。

Answer 1

尝试下行

messages.append(contentsOf: fetchedMessages) 

代替:messages.append(fetchedMessages)