Question

当用户点击自定义信息窗口时，我正试图将谷歌地图的userData传递到下一个视图。

首先我创建了这样的模型对象。

import UIKit
import Firebase

    struct Team {

        var key: String
        var teamName: String
        var league: String
        var lat: Double
        var lng: Double

        init(snapshot: DataSnapshot) {

            self.key = snapshot.key
            self.teamName = (snapshot.value as! NSDictionary)["teamName"] as? String
            self.league = (snapshot.value as! NSDictionary)["league"] as? String ?? ""
            self.lat = (snapshot.value as! NSDictionary)["lat"] as? Double ?? 0
            self.lng = (snapshot.value as! NSDictionary)["lng"] as? Double ?? 0
        }
    }

我获取数据库并将userData添加为

var teams = [Team?]()

    func fetchTeams(){

            let teamRef = Database.database().reference().child("teams")
            teamRef.observe(.value, with: { (snapshot) in
                var result = [Team]()

                for child in snapshot.children {
                    let child = Team(snapshot: child as! DataSnapshot)
                    result.append(child)
                    self.teams = result
                }

                for team in self.teams {
                    guard let lat = team?.lat else { return }
                    guard let lng = team?.lng else { return }
                    let marker: GMSMarker = GMSMarker()
                    marker.position = CLLocationCoordinate2DMake(lat, lng)
                    marker.map = self.mapView
                    marker.userData = team
                }

            }, withCancel: nil)
        }

此func完美无缺，因此我猜userData的属性正确无误。

func mapView(_ mapView: GMSMapView, markerInfoWindow marker: GMSMarker) -> UIView? {
            let infoWindow = Bundle.main.loadNibNamed("Marker", owner: self, options: nil)?.first as! MarkerView

            infoWindow.teamLabel.text = (marker.userData as! Team).teamName

            return infoWindow
        }


func mapView(_ mapView: GMSMapView, didTapInfoWindowOf marker: GMSMarker) {
        self.performSegue(withIdentifier: cellId, sender: self)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == cellId {
            let next: NextViewController = segue.destination as! NextViewController
            let marker = GMSMarker()
            next.team = marker.userData as? Team
        }
    }

我实现了如上所述将数据传递给NextViewController。它工作正常，直到performSegue，但next.team为零。有谁知道为什么？提前谢谢！

Answer 1

您遇到此问题是因为您正在创建一个空的GMSMarker，当然这个空的GMSMarker没有任何userData，您必须将选定的GMSMarker作为参数传递给performSegue，特别是sender参数，并投放为Team并将其传递给您的NextViewController

func mapView(_ mapView: GMSMapView, didTapInfoWindowOf marker: GMSMarker) {
        self.performSegue(withIdentifier: cellId, sender: marker.userData)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == cellId {
            let next: NextViewController = segue.destination as! NextViewController
            if let teamData = sender as? Team{
               next.team = teamData
               debugPrint("teamData is fine")
            }
            debugPrint("segue identifier is correct")
        }
    }

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