从Firebase数据库检索数据：发送到实例

Question

我有一个Firebase数据库，如下所示：

保存到数据库没有问题，但是当我尝试按以下方式检索数据时：

//Properties
@IBOutlet weak var bike1LBL: UILabel!
@IBOutlet weak var bike2LBL: UILabel!
@IBOutlet weak var bike3LBL: UILabel!
@IBOutlet weak var bike4LBL: UILabel!
@IBOutlet weak var chainLBL: UILabel!
@IBOutlet weak var brakeLBL: UILabel!
@IBOutlet weak var locationLBL: UILabel!
@IBOutlet weak var phoneLBL: UILabel!


override func viewDidLoad() {
    super.viewDidLoad()

    var ref = Firebase(url:"sdfghjkl/firebaseio.com/Order/")
    // Retrieve new posts as they are added to database
    ref.observeEventType(.ChildAdded, withBlock: { snapshot in

        let road = snapshot.value.objectForKey("Bike-Type1") as? String
        self.bike1LBL.text = road
        let city = snapshot.value.objectForKey("Bike-Type2") as? String
        self.bike2LBL.text = city
        let mountain = snapshot.value.objectForKey("Bike-Type3") as? String
        self.bike3LBL.text = mountain
        let christiania = snapshot.value.objectForKey("Bike-Type4") as? String
        self.bike4LBL.text = christiania
        let chain = snapshot.value.objectForKey("Chain") as? String
        self.chainLBL.text = chain
        let brake = snapshot.value.objectForKey("Brake") as? String
        self.brakeLBL.text = brake
        let location = snapshot.value.objectForKey("Location") as? String
        self.locationLBL.text = location
        let phone = snapshot.value.objectForKey("Phone") as? String
        self.phoneLBL.text = phone
        print(snapshot.value)
    })
}

应用程序崩溃，我收到此错误消息，但这是我从调试器获得的所有内容：

Answer 1

如果您更新到新的Firebase 3.0 api并查看MakinGIANTS - Post关于firebase和查询（它在Kotlin中，但“看起来像”Swift）并且可能有所帮助

会更好

Answer 2

来自Firebase docs：

  

您可以使用FIRDataEventTypeValue事件来读取数据   给定路径，因为它在事件发生时存在。这个方法是   每当听众被连接时再次触发一次   数据，包括任何儿童，都会发生变化事件回调传递a   包含该位置所有数据的快照，包括子数据。

所以snapshot实际上是Order中某些对象的数组，而不仅仅是最近添加的对象。尝试获取最后一个对象，然后从中获取数据：

ref.observeEventType(.ChildAdded, withBlock: { snapshot in
        let entry = (snapshot as! NSArray).lastObject as! NSDictionary
        let road = entry.objectForKey("Bike-Type1") as? String
        self.bike1LBL.text = road     
    })