获取用户位置和创建地图不同步

Question

以下代码获取用户当前位置并创建地图框地图。 问题是在获取用户位置之前正在创建 mapbox 地图。 如何减慢或同步此过程？ 提前谢谢你，

  import UIKit
  import CoreLocation
  import MapboxGL

 class AViewController: UIViewController, CLLocationManagerDelegate {
   var manager:CLLocationManager!
   var userLocation:CLLocation = CLLocation(latitude: 25.776243, longitude: -80.136509)

override func viewDidLoad() {
    super.viewDidLoad()

    println("inside viewdidload")
    self.getUserLocation()
}//eom

override func viewDidAppear(animated: Bool) {
    println("inside viewdidappear")
   self.createMapBoxMap()
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*** MapBox Functions ************************************************************************/
    /*Create preliminary map */
    func createMapBoxMap(){
        // set your access token
        let mapView = MGLMapView(frame: view.bounds, accessToken: "pk.eyJ1IjoiZGFya2ZhZGVyIiwiYSI6IlplVDhfR3MifQ.pPEz732qS8g0WEScdItakg")

        mapView.autoresizingMask = .FlexibleWidth | .FlexibleHeight

        // set the map's center coordinate
        mapView.setCenterCoordinate(CLLocationCoordinate2D(latitude: self.userLocation.coordinate.latitude, longitude: self.userLocation.coordinate.longitude),
            zoomLevel: 13, animated: false)
        view.addSubview(mapView)

        //showing the user location on map - blue dot
        mapView.showsUserLocation = true
    }//eom


/*** location Functions ************************************************************************/
    /*getting user current location*/
    func getUserLocation(){
        self.manager = CLLocationManager()
        self.manager.delegate = self
        self.manager.desiredAccuracy = kCLLocationAccuracyBest
        self.manager.requestWhenInUseAuthorization()
        self.manager.startUpdatingLocation()
    }//eom

    /*location manager 'didUpdateLocations' function */
    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        self.manager.stopUpdatingLocation() //stop getting user location
        println(locations)

        self.userLocation = locations[0] as! CLLocation

    }//eom

    /* errors occurred */
    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError) {
        println("Error:" + error.localizedDescription)
    }//eom

}//eoc

Answer 1

位置管理器正在异步运行（预期行为），这意味着它会立即返回并在调用创建地图框方法后立即完成创建地图。但是，这并不意味着地图已经获得了位置。我认为实现这一点的最佳方法是将self.createMapBoxMap() 移动到didUpdateLocations 内部并尝试。根据我的经验，您希望在像这样的异步方法的回调中创建视图。不过，您可能希望拥有某种类型的加载视图，因为用户一开始会感到困惑。