json - 注释未显示在 map 上

Question

我正在尝试使用来自服务器的位置列表在 map 上添加注释。

Json 数据:

[{ "_id" : "589f3e299b64795df23a886b",
   "name" : "Store 1",
   "description" : "Most awesome store!",
   "location" : {
       "longitude" : -6.279025369998967,
       "latitude" : 53.35487382895707
   }
},
{
   "_id" : "589f3e299b64795df23a886b",
   "name" : "Store 2",
   "description" : "Most awesome store!",
   "location" : {
      "longitude" : -6.267085527951536,
      "latitude" : 53.33785738724761
   }
}]

我正在使用 alamo fire 从服务器发送 get 请求，以在 viewWillAppear 方法中获取上面的 json 数据。

    override func viewWillAppear(_ animated: Bool) {
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.requestWhenInUseAuthorization()
    locationManager.requestLocation()
    mapView.showsUserLocation = false

    var currentLocation = Location()
    if let location = locationManager.location {
        currentLocation = Location(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
    }

    //default to 10 km radius for now
    let params = [
            "latitude": currentLocation.getLatitude(),
            "longitude": currentLocation.getLongitude(),
            "radius": 10.0
    ] as [String : Any]

    Alamofire.request("http://website.com/fyp/searchNearbyStores", parameters: params).responseJSON { response in
        switch response.result {
        case .success(let value):
            let result = JSON(value)
            print(result)
            self.storeList = result.arrayValue.map({

                Store(name: $0["name"].stringValue, description: $0["description"].stringValue, location: CLLocationCoordinate2D(latitude: $0["location"]["latitude"].doubleValue, longitude: $0["location"]["longitude"].doubleValue))
            })

        case .failure(let error):
            print(error)
        }
    }
}

最后，在 viewDidLoad 方法中，我使用带有纬度/经度数据的 storeList 来添加注释。

   override func viewDidLoad() {
    super.viewDidLoad()

    //zoom to current user location
    if let location = locationManager.location {
        let span = MKCoordinateSpanMake(0.01, 0.01)
        let region = MKCoordinateRegion(center: location.coordinate, span: span)
        mapView.setRegion(region, animated: true)
    }
    for store in storeList {
        let annotation = MKPointAnnotation()
        annotation.title = store.getName()
        annotation.subtitle = store.getDescription()
        annotation.coordinate = store.getLocation()
        mapView.addAnnotation(annotation)
    }
}

由于某种原因，当我运行它时，注释似乎没有显示在 map 中。我似乎正在以正确的方式添加注释，但可能错过了一个小但重要的部分。有人可以帮忙吗？

Answer 1

您使用的viewWillAppear错误。您应该在 viewDidLoad 中发出请求，并在请求函数内执行此操作(加载数据后)

if let location = locationManager.location {
    let span = MKCoordinateSpanMake(0.01, 0.01)
    let region = MKCoordinateRegion(center: location.coordinate, span: span)
    mapView.setRegion(region, animated: true)
}
for store in storeList {
    let annotation = MKPointAnnotation()
    annotation.title = store.getName()
    annotation.subtitle = store.getDescription()
    annotation.coordinate = store.getLocation()
    mapView.addAnnotation(annotation)
}

因为 viewDidLoad 在 viewWillAppear 之前调用，并且因为 Alamofire 请求是异步，这意味着它将在 viewDidLoad 和 viewWillAppear 之后完成。因此，当您添加注释和下载数据时，您的数组为空，什么也没有发生