Question

我有一个应用程序，允许用户在地图上的任何地方放置一个引脚（MapKit），它当前识别并显示它们的当前位置。我想设置一个约束，以便用户无法在距当前位置10英里的范围内丢弃一个引脚。这可行吗？我对dev很新，所以我不知道从哪里开始这样做。这里有一些处理drop pin的代码：

@IBOutlet weak var mapView: MKMapView!


//addpin
@IBAction func addPin(sender: UILongPressGestureRecognizer) {


//locating where to drop the pin
    let location = sender.locationInView(self.mapView)
    let locCoord = self.mapView.convertPoint(location, toCoordinateFromView:
         self.mapView)

    let annotation = MKPointAnnotation()
    annotation.coordinate = locCoord
    annotation.title = "Test"
    annotation.subtitle = "subtext"

//remove map point (use later)

     self.mapView.removeAnnotations(mapView.annotations)

     self.mapView.addAnnotation(annotation)

}

Answer 1

您可以使用distance(from: )方法。

请参阅：https://developer.apple.com/documentation/corelocation/cllocation/1423689-distance

@IBAction func addPin(sender: UILongPressGestureRecognizer) {

    //locating where to drop the pin
    let location = sender.locationInView(self.mapView)
    let locCoord = self.mapView.convertPoint(location, toCoordinateFromView:
     self.mapView)

    // Get distance between pressed location and user location
    let pressedLocation = CLLocation(latitude: locCoord.latitude, longitude: locCoord.longitude)
    // let distanceInMeters = self.mapView.userLocation.location?.distance(from: pressedLocation) // >= Swift 3
    let distanceInMeters = self.mapView.userLocation.location?.distanceFromLocation(pressedLocation) // < Swift 3

    // You get here distance in meter so 10 miles = 16090 meter
    if let distanceInMeters = distanceInMeters, distanceInMeters > 16090 {
        // out of 10 mile (don't drop pin)
        return
    }

    let annotation = MKPointAnnotation()
    annotation.coordinate = locCoord
    annotation.title = "Test"
    annotation.subtitle = "subtext"

    //remove map point (use later)

    self.mapView.removeAnnotations(mapView.annotations)

    self.mapView.addAnnotation(annotation)

}

但是，您需要先做好几件事。

您需要ask the user for permission才能使用其位置。这包括调用CLLocationManager的requestWhenInUseAuthorization并检查异步结果。
在您的信息中添加NSLocationWhenInUseUsageDescription条目（在上面的链接中描述），告诉用户您要对信息做什么

MapKit-如何添加位置约束以丢弃引脚？

1 个答案: