ios - 从 Firebase Swift 检索双数字时出现问题

Question

我目前正在开展餐厅项目，通过按餐厅 View Controller 上的按钮，我可以在谷歌地图( map View Controller )上查看餐厅的位置。为了将纬度和经度放入我的 map 代码中，我在从 Firebase 检索 Double 数字时遇到问题。每当我尝试打印它们时，我都会收到此错误“ fatal error :在展开可选值 (lldb) 时意外发现 nil”

GMSServices.provideAPIKey("AIzaSyRQKeLyKH5CsrDPpPsjy7nYqudEbqXmQS2")
        let ref = Database.database().reference().child("amsterdam")
        ref.queryOrdered(byChild: "name").queryEqual(toValue: self.appDelegate.selectedBarName).observe(.value) { (snapshot) in
            for child in snapshot.children{
                let snap = child as! DataSnapshot
                let mapSnap = snap.childSnapshot(forPath: "map")
                if let snapDict = mapSnap.value as? [String:AnyObject]{
                    let dictValues = [AnyObject](snapDict.values)
                    for each in dictValues{
                        let latitude = each["map_latitude"] as! Double
                        let longitude = each["map_longitude"] as! Double

                        print(latitude)
                        print(longitude)
                       let camera = GMSCameraPosition.camera(withLatitude: latitude, longitude: longitude, zoom: 6.0)
                        let mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
                        self.view = mapView
                        let marker = GMSMarker()
                        marker.position = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
                        marker.map = mapView
                    }
            }
        }
    }
}

Answer 1

我认为问题在于从每个中获取值(value)。尝试使用此行获取 each 作为字典对象的值。

let latitude = each.object(forKey:"map_latitude") as! Double