Firebase数据到tableview,追加数据后崩溃

时间:2019-04-26 11:05:28

标签: swift firebase firebase-realtime-database append

我正在尝试使用

从Firebase下载数据

firebaseDB.observe(DataEventType.value, with: { (snapshot) in })

效果很好。我能够收到以下数据:

let fetchedObject = items.value as? [String: AnyObject]
let dbUrl = fetchedObject?["url"]
let dbTime = fetchedObject?["time"]
let dbStatus = fetchedObject?["status"]

使用print("\(dbUrl!), \(dbTime!), \(dbStatus!)"),我在控制台中看到以下输出:

  

https://google.de,2019-04-26 07:44:54 +0000,新

但是,因为我想在Tableview中显示数据,所以我为数据模型创建了一个名为ItemModel的快速文件,其内容如下:

class ItemModel {

    var url: String?
    var time: String?
    var status: String?

    init(url: String?, time: String?, status: String?){

        self.url = url
        self.time = time
        self.status = status

    }
}

当尝试使用填充网址,时间和状态时

let item = ItemModel(url: dbUrl as! String?, time: dbTime as! String?, status: dbStatus as! String?)

self.itemList.append(item)附加它,并用self.tableViewOutlet.reloadData()重新加载表,应用程序崩溃。

如果我将self.itemList.append(item)注释掉,它不会崩溃。

我在做什么错?我显然错过了一些可行的方法,但是我只是想不出什么。我真的很想知道为什么附加数据不起作用...非常感谢您的帮助!

编辑:

完整的提取方法:

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

var itemList = [ItemModel]()

override func viewDidLoad() {

        super.viewDidLoad()

        [...]

        // Authenticate user
        Auth.auth().signInAnonymously() {(authResult, error) in

            if error == nil {

                self.user = authResult!.user // Authenticate User
                self.uid = self.user.uid // Users unique and anonymous identifier by Firebase
                print(">> LOG: Auth success!")

                // Download data from Firebase
                var itemsDB: DatabaseReference!
                itemsDB = Database.database().reference().child("somechild").child("someotherchild")
                itemsDB.observe(DataEventType.value, with: { (snapshot) in

                    // Check if there is any relevant data
                    if snapshot.childrenCount > 0 {

                        // Initially clear the list
                        self.itemList.removeAll()

                        // Interate through all the values
                        for items in snapshot.children.allObjects as! [DataSnapshot] {

                            // Get the values from Firebase
                            let fetchedObject = items.value as? [String: AnyObject]
                            let dbUrl  = fetchedObject?["url"]
                            let dbTime = fetchedObject?["time"]
                            let dbStatus = fetchedObject?["status"]

                            let item = ItemModel(url: dbUrl as? String, time: dbTime as? String, status: dbStatus as? String)
                            print("\(item.url!), \(item.time!), \(item.status!)")
                            self.itemList.append(item)

                        }

                        // Reload the Tableview
                        self.tableViewOutlet.reloadData()
                    }
                })

            } else {

                print(">> LOG: Error when trying to authenticate: \(error!)")

            }

        }

    }

}

0 个答案:

没有答案