Swift 将自定义对象附加到数组并对其进行排序

Question

我正在制作一个收藏视图，向某人显示他们的“供稿”，其中包括他们的赞美、喜欢、回复和发送。我有一个名为 Feed 的对象，它由一组赞美、一组喜欢、一组回复和一组发送组成。这些较小数组中的每个对象都有一个 date_created 属性。

我知道如何根据一个按日期排序的数组填充集合视图，但是如何根据发送日期从四个数组加载每个喜欢、回复、赞美和发送的集合视图？

我是否可能将这些对象中的每一个都附加到一个数组中？如果是这样，我该如何遍历该数组并对其中的所有内容进行排序？

struct Feed: Decodable {
    let likes: [Like]
    let replies: [Reply]
    let compliments: [Compliment]
    let sent: [Compliment]
}

struct Like: Decodable {
    let id: Int
    let user: QuickUser
    let created_at: String
}

struct Reply: Decodable {
    let parent: Compliment
    let content: String
    let created_at: String
}

struct Compliment: Decodable {
    let id: Int
    let content: String
    let sender: QuickUser

    let created_at: String

    let is_liked: Bool
    let recipient: QuickUser
    let is_public: Bool
}

func getFeed() {
    UserServices.getInboxFeed { feed in
        guard let feed = feed else {
            self.showOkayAlert(title: "Oops!", message: "We are having trouble loading your inbox.", completion: nil)
            return
        }
        self.feed = feed

        DispatchQueue.main.async {
            //load collection view here
        }
    }
}

集合视图的样机

Answer 1

好吧，为了解决这个问题，我制作了一个虚拟协议，其中包含它们共享的共享属性。

在这种情况下是created_at，我认为这应该是日期格式。

不过，下一步是扩展 Feed，其中包含 function

返回与我调用的虚拟protocol 确认的最新对象，它是LatestAction，

它基本上按date 对每个数组进行排序并返回第一项。

在我们的例子中是最新的date，

然后创建一个[LatestAction] 以同样的方式再次对其进行排序并返回第一个项目，即LatestAction。

观察下面的代码。

struct QuickUser: Codable {

}

struct Feed: Decodable {
    let likes: [Like]
    let replies: [Reply]
    let compliments: [Compliment]
    let sent: [Compliment]
}
extension Feed {
    func latestAction() -> LatestAction {
        let latestLike = self.likes.sorted(by: { $0.created_at.compare($1.created_at) == .orderedDescending }).first!
        let latestReply = self.replies.sorted(by: { $0.created_at.compare($1.created_at) == .orderedDescending }).first!
        let latestComp = self.compliments.sorted(by: { $0.created_at.compare($1.created_at) == .orderedDescending }).first!
        let latestActions: [LatestAction] = [latestReply, latestLike, latestComp].sorted(by: { $0.created_at.compare($1.created_at) == .orderedDescending })
        return latestActions.first!
    }

}
protocol LatestAction  {
    var created_at: Date { get }
}

struct Like: Decodable, LatestAction {

    let id: Int
    let user: QuickUser
    let created_at: Date
}

struct Reply: Decodable, LatestAction {

    let parent: Compliment
    let content: String
    let created_at: Date
}

struct Compliment: Decodable, LatestAction {

    let id: Int
    let content: String
    let sender: QuickUser

    let created_at: Date

    let is_liked: Bool
    let recipient: QuickUser
    let is_public: Bool
}



// Simply used like this
var latest = feed.latestAction() 

如果您检查了latest 类型，我们还没有完成，它会说LatestAction，并且只能访问其中的一个属性，即created_at，

现在是最后一部分，我们要去TypeCastObject。

if let latest = feed.latestAction() as? Like {
    // used as Like
} else if let latest = feed.latestAction() as? Compliment {
    // used as Compliment
} else if let latest = feed.latestAction() as? Reply {
    // used as reply
}