ios - 如果我直接实例化 VC，setRegion() 不起作用，但如果我通过 segue Swift 4 访问 VC，setRegion() 则不起作用

Question

我正在尝试一个函数行为的奇怪的(在我看来)改变，这取决于我如何到达包含它的 VC。当用户点击远程通知操作时，应用程序从后台转到前台，转到NewMapViewController ，加载一条路线，将其显示为 MKPolyline并根据MKPolyline设置区域MapRect 。现在我面临的问题是setRegion()不起作用取决于我如何到达 NewMapViewController 。如果在操作中我实例化主 UINavigationController并访问 NewMapController通过 segue 比 setRegion在displayRoute()按预期工作，但我看到 loginVC在展示之前。所以不显示loginVC我改为实例化 NewMapViewController直接，但这样做setRegion在displayRoute()无法放大MKPolyline不再了。为什么会发生这种情况？起初我以为configureMap (以用户位置为中心的 map )被调用但没有，所有打印显示当 NewMapViewController当计数器加载到 1 时，它永远不会被调用。我尝试使用 setVisibleMapRect()而不是setRegion()但这没有什么区别。这是一个已知的错误吗？还有其他方法可以到达 newMapViewController我应该尝试吗？一如既往，非常感谢您的时间和帮助。

更新:

经过几次尝试，我决定调用 checkAlerts()直接来自 Action 体，而不是来自 viewWillApper()柜台检查。添加 MKPolyline 时导致零错误在displayRoute() 。搜索了一下我发现这是一个线程问题，因此将其添加到 DispatchQueue.main.async 中排队一切再次按预期工作。无论我调用 checkAlerts() 都有效来自 Action 主体或来自 viewWillApper()柜台检查。看来当我实例化UINavigationController时并转到NewMApController通过segue，它有时间加载路线并计算折线，但是直接实例化时NewMapController才不是。我想更好地理解它，这对您来说有意义吗？

这是操作:

case Id.checkActionIdentifier:
            print("Check tapped")
            let userInfo = response.notification.request.content.userInfo
            if let routeToCheck = userInfo[NSLocalizedString("Route", comment: "")] as? String {
                RoutesArray.routeName = routeToCheck
//                print("rotta is: \(routeToCheck)")
            }
//            let content = response.notification.request.content
//            print(" Body \(content.body)")
//            print(" Title \(content.title)")
            NewMapViewController.routeCheckCounter = 1

            //  Goes to NewMapViewController but showing the loginVc first
//            let storyboard = UIStoryboard(name: "Main", bundle: nil)
//            let initialViewController : UINavigationController = storyboard.instantiateViewController(withIdentifier: "MainNavigationController") as! UINavigationController
//            self.window?.rootViewController = initialViewController
//            self.window?.makeKeyAndVisible()
//            let vc = initialViewController.viewControllers[0]
//            vc.performSegue(withIdentifier: "alertToMapSegue", sender: nil)

            // setRegion in displayRoute() not working ???
            if let navigationVC = self.window?.rootViewController as? UINavigationController {
                let main = UIStoryboard(name: "Main", bundle: nil)
                let newMapVC = main.instantiateViewController(withIdentifier: "NewMapViewController") as! NewMapViewController
                navigationVC.pushViewController(newMapVC, animated: true)
            }

这是显示 MKPolyline 的函数:

func displayRoute() {
        print("displayRoute called")
        var coordinateArray: [CLLocationCoordinate2D] = []
        for point in MapArray.actualRouteInUseCoordinatesArray {
            let location = CLLocationCoordinate2D(latitude: point.coordinate.latitude, longitude: point.coordinate.longitude)
            coordinateArray.append(location)
        }
        // tracked CLLocations route
        routePolyline = MKGeodesicPolyline(coordinates: coordinateArray, count: coordinateArray.count)
        mapView.add(routePolyline, level: MKOverlayLevel.aboveRoads)
        let startRouteAnnotation: RouteAnnotation = RouteAnnotation(title: "Route Start", coordinate: MapArray.actualRouteInUseCoordinatesArray.first!.coordinate)
        self.mapView.addAnnotation(startRouteAnnotation)

        let endRouteAnnotation = RouteAnnotation(title: "Route End", coordinate: MapArray.actualRouteInUseCoordinatesArray.last!.coordinate)
        self.mapView.addAnnotation(endRouteAnnotation)

        print("MapArray.actualRouteInUseCoordinatesArray.count is: \(MapArray.actualRouteInUseCoordinatesArray.count)")


        // full display
        let region = MKCoordinateRegionForMapRect(routePolyline!.boundingMapRect)
        mapView.setRegion(region, animated: true)

        // padded in
//        self.mapView.setRegion(MKCoordinateRegionForMapRect(padMapRect(rect: routePolyline.boundingMapRect)), animated: true)
    }

这就是我如何调用 viewWillAppear() 处的函数:( checkAlerts() 比调用 displayRoute() 。

// if loading vc from an scheduled alert check notification
        print(" CheckCounter is: \(NewMapViewController.routeCheckCounter ?? 0)")
        if NewMapViewController.routeCheckCounter ?? 0 > 0 {
            print("checkAlerts called in viewDidLoad")
            // load the route and call displayRoute()
            checkAlerts()
        } else {
            // just center map on user location
            configureMap()
            return
        }

Answer 1

在我的问题的更新部分中描述的尝试之后，这里是修改后的函数，其工作方式正如预期的那样:

func displayRoute() {
        print("displayRoute called")
        var coordinateArray: [CLLocationCoordinate2D] = []
        for point in MapArray.actualRouteInUseCoordinatesArray {
            let location = CLLocationCoordinate2D(latitude: point.coordinate.latitude, longitude: point.coordinate.longitude)
            coordinateArray.append(location)
        }
        DispatchQueue.main.async {
        // tracked CLLocations route
        self.routePolyline = MKGeodesicPolyline(coordinates: coordinateArray, count: coordinateArray.count)
        self.mapView.add(self.routePolyline, level: MKOverlayLevel.aboveRoads)

        let startRouteAnnotation: RouteAnnotation = RouteAnnotation(title: "Route Start", coordinate: MapArray.actualRouteInUseCoordinatesArray.first!.coordinate)
        self.mapView.addAnnotation(startRouteAnnotation)

        let endRouteAnnotation = RouteAnnotation(title: "Route End", coordinate: MapArray.actualRouteInUseCoordinatesArray.last!.coordinate)
        self.mapView.addAnnotation(endRouteAnnotation)

        print("MapArray.actualRouteInUseCoordinatesArray.count is: \(MapArray.actualRouteInUseCoordinatesArray.count)")
//        self.mapView.setRegion(MKCoordinateRegionForMapRect(padMapRect(rect: routePolyline.boundingMapRect)), animated: true)

        self.mapView.setVisibleMapRect(self.padMapRect(rect: self.routePolyline.boundingMapRect), animated: true)
        }
    }