如何在初始化后从函数中获取值？

Question

我从Firebase获取坐标，然后我将它们放在我的地图上，但问题是我的Firebase取指令发生在地图初始化标记后，在我的坐标中给出nil。

如何从Firebase获取值并将其作为标记？

var fetchLat: Double!
var fetchLong: Double!

在这里，我从Firebase获取值

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
{
    let camera = GMSCameraPosition.camera(withLatitude: latPass, longitude: longPass, zoom: 5)
    let mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
    view = mapView
    mapView.settings.scrollGestures = true
    mapView.settings.zoomGestures = true
    mapView.settings.myLocationButton = true

    let dataBaseRef=FIRDatabase.database().reference()
    dataBaseRef.child("LocationTest").queryOrderedByKey().observe(.childAdded, with: {(snapshot) in

        let postDict = snapshot.value as? [String : AnyObject] ?? [:]
        var fetchLat = postDict["lat"] as! Double
        var fetchLong = postDict["long"] as! Double
})

我将它们放在地图上

    let friendLocator = [
        Locator(name: "Virat", long: fetchLong, lat: fetchLat),
    ]

    for friend in friendLocator{

        let friendMarker = GMSMarker()
        friendMarker.position=CLLocationCoordinate2D(latitude: friend.lat, longitude: friend.long)
        friendMarker.title=friend.name
        friendMarker.map=mapView
        mapView.selectedMarker=friendMarker
    }

由于地图初始化是在从Firebase获取值之前完成的，因此如何在获取值后设置标记？

Answer 1

如果在地图上显示用户的ViewController与LocationManager的委托相同，那么

在ViewController中创建一个属性

var friendLocator : [Locator] = [Locator]()

创建一个在地图上绘制用户的功能

func locateFriends() {
        if self.view is GMSMapView {
            for friend in friendLocator {
                let friendMarker = GMSMarker()
                friendMarker.position=CLLocationCoordinate2D(latitude: friend.lat, longitude: friend.long)
                friendMarker.title=friend.name
                friendMarker.map= (self.view as! GMSMapView)
                (self.view as! GMSMapView).selectedMarker=friendMarker
            }
        }
    }

最后将新找到的定位器实例附加到didUpdateLocations委托

中的数组

extension ViewController : UIPageViewControllerDelegate {
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
    {

        let dataBaseRef=FIRDatabase.database().reference()
        dataBaseRef.child("LocationTest").queryOrderedByKey().observe(.childAdded, with: {(snapshot) in

            let postDict = snapshot.value as? [String : AnyObject] ?? [:]
            var fetchLat = postDict["lat"] as! Double
            var fetchLong = postDict["long"] as! Double

            let locator = Locator(name: "Virat", long: fetchLong, lat: fetchLat)
            //do some sort of duplicate check before blindly adding new locator to array
            self.friendLocator.append(locator)
            self.locateFriends()
        })
    }
}

如果在地图上显示用户的ViewController不同，那么UILocationManager委托的那个使用相同的逻辑，而是使用delegate模式通知ViewController新的定位器对象并重新加载地图。

修改

重新格式化OP的代码

import MapKit

import UIKit

import CoreLocation

import GoogleMaps

import GooglePlaces

import GoogleMapsCore

import Firebase

import FirebaseDatabase


struct postStruct{

    let lat: Double!

    let long: Double!

}


class ViewController: UIViewController,MKMapViewDelegate, CLLocationManagerDelegate, UISearchBarDelegate{


    var viratPin=CustomPointAnnotation()

    var posts=[postStruct]()
    var mapView : GMSMapView? = nil


    var friendLocator : [Locator] = [Locator]()



    @IBOutlet weak var searchBar: UISearchBar!

    @IBOutlet weak var searchSupporter: UIView!

    @IBAction func dismissKeyboard(_ sender: Any) {

        searchBar.resignFirstResponder()

    }



    struct Locator {

        let name: String

        let long: CLLocationDegrees

        let lat: CLLocationDegrees

    }



    class CustomPointAnnotation: MKPointAnnotation {

        var imageName: String!

    }



    let manager = CLLocationManager()

    var myLocation: CLLocationCoordinate2D?

    var friend1: CLLocationCoordinate2D?

    var arbokPin = CustomPointAnnotation()

    var location=0

    var latPass: Double!

    var longPass: Double!

    var fetchLat: Double!

    var fetchLong: Double!



    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])

    {

        var location=locations[0]

        let span:MKCoordinateSpan=MKCoordinateSpanMake(0.01, 0.01)

        var myLocation:CLLocationCoordinate2D=CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)

        let region:MKCoordinateRegion=MKCoordinateRegionMake(myLocation, span)

        latPass=location.coordinate.latitude

        longPass=location.coordinate.longitude


        post()

        self.configureMapView()

        let dataBaseRef=FIRDatabase.database().reference()

        dataBaseRef.child("LocationTest").queryOrderedByKey().observe(.childAdded, with: {(snapshot) in



            let postDict = snapshot.value as? [String : AnyObject] ?? [:]

            var fetchLat = postDict["lat"] as! Double

            var fetchLong = postDict["long"] as! Double


            let locator = Locator(name: "You", long: fetchLong, lat: fetchLat)
            self.friendLocator.append(locator)
            self.locateFriend()
        })

        manager.stopUpdatingLocation()

        self.view = mapView
    }


    func configureMapView() {
        let camera = GMSCameraPosition.camera(withLatitude: latPass, longitude: longPass, zoom: 5)

        self.mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)

        view = mapView

        mapView.settings.scrollGestures = true

        mapView.settings.zoomGestures = true

        mapView.settings.myLocationButton = true

        mapView.addSubview(searchBar)

        mapView.addSubview(searchSupporter)

        mapView.bringSubview(toFront: searchBar)


        for gesture in mapView.gestureRecognizers! {

            mapView.removeGestureRecognizer(gesture)

        }
    }

    func locateFriend() {
        for friend in friendLocator{
            let friendMarker = GMSMarker()

            friendMarker.position=CLLocationCoordinate2D(latitude: friend.lat, longitude: friend.long)

            friendMarker.title=friend.name

            friendMarker.map=mapView

            mapView.selectedMarker=friendMarker

            if friend.name=="Virat"{

                friendMarker.icon=UIImage(named: "ViratPin.png")

            }

            else if friend.name=="Naveen"{

                friendMarker.icon=UIImage(named: "naveenPin.png")

            }

            else if friend.name=="You"{

                friendMarker.icon=UIImage(named: "currentLocation.png")

            }

        }

        do {

            mapView.mapStyle = try GMSMapStyle(jsonString: kMapStyle)

        } catch {

            NSLog("One or more of the map styles failed to load. \(error)")

        }
    }

    override func viewDidLoad() {

        super.viewDidLoad()



        manager.delegate=self

        manager.desiredAccuracy=kCLLocationAccuracyBest

        manager.requestWhenInUseAuthorization()

        manager.startUpdatingLocation()

        searchBar.isUserInteractionEnabled=true

        searchBar.delegate=self

        searchSupporter.alpha=0



    }





    func searchBarTextDidBeginEditing(_ searchBar : UISearchBar){

        self.searchSupporter.alpha=0.8

        print("yes")

    }



    func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {

        searchSupporter.alpha=0

        print("no")

    }



    func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {

        print(searchBar.text!)


    }


    override var prefersStatusBarHidden: Bool{

        return true

    }

    func post(){

        let post : [String: Double]=["lat":latPass, "long":longPass]

        let dataBaseRef=FIRDatabase.database().reference()

        //dataBaseRef.child("Location").childByAutoId().setValue(post)

        dataBaseRef.child("Location").child("id").setValue(post)


    }
}