使用mapKit Swift显示与用户的距离(英里/公里)

Question

我一直试图在tableView上显示距离，但无法实现。这个问题是在这个问题之后提出的：CLLocationDistance转换。我检查了一下距离。在我的Location类中使用此函数：

// Get distance
func distance(to location: CLLocation) -> CLLocationDistance {
return location.distance(from: self.location)
}

如何获取用户当前位置：

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let location = locations[0]
let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01)
let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
mapView.setRegion(region, animated: true)
// Add a lastUserLocation to LocationManager and update it every time that the delegate receives a new location
LocationManager.shared.lastUserLocation = locations.last
LocationManager.shared.sortLocationsInPlace()
self.mapView.showsUserLocation = true
}

LocationManager:中的排序功能

func getSortedLocations(userLocation: CLLocation) -> [Location] {
return locations.sorted { (l1, l2) -> Bool in
return l1.distance(to: userLocation) < l2.distance(to: userLocation)
}
}
func sortLocationsInPlace() {
if let validLocation = lastUserLocation {
locations.sort { (l1, l2) -> Bool in
return l1.distance(to: validLocation) < l2.distance(to: validLocation)
} 
}
}

cellForRowAt:

var sortedLocations = [Location]()
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "locationCell", for: indexPath)

let location = sortedLocations[indexPath.row]
cell.textLabel?.text = location.name
return cell
}

更新

内部Location类：

class Location {
var name: String
var latitude: Double
var longitude: Double
var location:CLLocation {
return CLLocation(latitude: latitude, longitude: longitude)
}
init?(json: JSON) {
guard let name = json["name"] as? String, let latitude = json["latitude"] as? Double, let longitude = json["longitude"] as? Double else { return nil }
self.name = name
self.latitude = latitude
self.longitude = longitude
}
func distance(to location: CLLocation) -> CLLocationDistance {
return location.distance(from: self.location)
}
}

Answer 1

考虑到您的代码，我做了一些假设：

1. 您的sortedLocations数组具有不同的位置，这些位置是从JSON或其他位置提取的
2. 在加载数据之前，您可以调用startUpdatingLocation()或类似的方法
3. 您正在接收didUpdateLocations中的更新
4. 您的LocationManager将所有位置的有序副本保存在一个名为locations的变量中，该变量是您在didUpdateLocations中订购的

考虑到，我理解您想要做的是显示根据参考位置订购的sortedLocations。

缺少的是在收到用户位置后更新UITableView数据。您有两个主要选项：

1. 只有在didUpdateLocations检索到您的第一个用户位置后才加载UITableView
2. 要在获得新位置后强制更新UITableView，请在didUpdateLocations中调用tableView.reloadData()。这将在每次收到位置更新时重新绘制列表，并按位置进行排序

但是在任何情况下，您都需要替换cellForRow文本来显示距离，而不是location.name:

// Distance in meters
cell.textLabel?.text = String(location.distance(to: LocationManager.shared.lastUserLocation!))
// Distance in miles
cell.textLabel?.text = String(location.distance(to: LocationManager.shared.lastUserLocation!)*0.00062137)

并且更新您的didUpdateLocations:

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
if let location = locations.last {
let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01)
let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
mapView.setRegion(region, animated: true)
// Add a lastUserLocation to LocationManager and update it every time that the delegate receives a new location
LocationManager.shared.lastUserLocation = location
LocationManager.shared.sortLocationsInPlace()
sortedLocations = LocationManager.shared.locations
tableView.reloadData()
self.mapView.showsUserLocation = true
}
}

使用当前代码，您将所有距离与self.location变量进行比较，该变量显然没有在任何地方初始化。