ios - 模型类 Swift 中的完成处理程序

Question

我正在将 MVC 用于我的 Firebase 应用。现在在 Model 类中，我想显示一个包含从 Firebase 检索的数据的 TableView。每个单元格都有一个关联的图像。现在的问题是我找不到让图像显示在tableview中的方法。下载图像在后端，我找不到显示它的方法。

class List {
    let ref:DatabaseReference?
    var name : String
    var title : String
    var subtitle : String
    var time : String
    var puretime : Any
    var indexOfSelf : String
    lazy var photo : UIImage = UIImage()

    init(name: String, title: String, subtitle: String, time: String, puretime: Any, indexOfSelf: String, photo: UIImage) {
        self.ref = nil
        self.name = name
        self.title = title
        self.subtitle = subtitle
        self.time = time
        self.puretime = puretime
        self.indexOfSelf = indexOfSelf
        self.photo = photo
    }
    typealias CompletionHandler = (_ success:Bool) -> Void
    init?(snapshot: DataSnapshot)
    {
        guard
        let value = snapshot.value as? [String: AnyObject],
        let url = value["0"] as? String,
        let name = value["name"] as? String,
        let title = value["title"] as? String,
        let subtitle = value["subtitle"] as? String,
        let time = value["time"] as? String,
        let puretime = value["puretime"] as? Any,
        let indexOfSelf = value["indexOfSelf"] as? String
        else{
            return nil
        }

        self.ref = snapshot.ref
        self.name = name
        self.title = title
        self.subtitle = subtitle
        self.time = time
        self.puretime = puretime
        self.indexOfSelf = indexOfSelf
        var image = UIImage()

    }
    var image = UIImage()
    func getImage(url:String, completionHandler: @escaping CompletionHandler) {
        print("Doing something!")

        let storageRef = Storage.storage().reference(forURL: url)
        storageRef.getData(maxSize: 1 * 2084 * 2084)
        { data, error in
            if let error = error {
                print("error from downloading image is \(error)")

            } else {
                self.image = UIImage(data: data!)!
                let flag = true
                completionHandler(flag)
            }

        }

    }

    func toAnyObject() -> Any{
        return [
            "name": name,
            "title": title,
            "subtitle": subtitle,
            "time": time,
            "puretime": puretime,
            "indexOfSelf": indexOfSelf,
            "photo": photo
        ]
    }
}

除了图像之外，所有其他实体都在工作。我不太确定如何在我的案例中使用完成功能。那么有人可以给我一些建议吗？非常感谢

Answer 1

创建一个服务类并添加一个方法，如下所示(我还建议将 List 创建为结构体，而不是类。)

class YourServiceClass {
    func getItemList(completion: @escaping (Array< List >?,Error?)-> Void)
    {
      //call your get service and inside you service response
      //check for all your validation here  is a success then

        let listElms = arrayOfItems.compactMap(List.init)
        completion(listElms,nil)

    }
}

现在从您的 viewController 或 viewModel 调用 getItemList。