MKMapKit可拖动的注释和绘制多边形

我目前正试图让用户添加引脚到地图上，然后绘制一个连接这些引脚的多边形。 不过，我想扩展它，让用户能够拖动引脚和多边形将相应地更新。 MKMapView根据它们在数组中的排列从坐标数组中绘制多边形（如果我没有弄错的话）。 我现在面临的问题是如何在用户重新定位引脚后更新多边形。

var touchCoordinatesWithOrder: [(coordinate: CLLocationCoordinate2D, order: Int)] = [] var counter = 0 func addLongPressGesture() { let longPressRecogniser = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress)) longPressRecogniser.minimumPressDuration = 1.0 mapView.addGestureRecognizer(longPressRecogniser) } func handleLongPress(gestureRecognizer: UIGestureRecognizer) { if gestureRecognizer.state != .Began { return } let touchPoint = gestureRecognizer.locationInView(self.mapView) let touchMapCoordinate = mapView.convertPoint(touchPoint, toCoordinateFromView: mapView) let annotation = MKPointAnnotation() annotation.coordinate = touchMapCoordinate mapView.addAnnotation(annotation) touchCoordinatesWithOrder.append((coordinate: touchMapCoordinate, order: counter)) counter += 1 } @IBAction func drawAction(sender: AnyObject) { if touchCoordinatesWithOrder.count <= 2 { print("Not enough coordinates") return } var coords = [CLLocationCoordinate2D]() for i in 0..<touchCoordinatesWithOrder.count { coords.append(touchCoordinatesWithOrder[i].coordinate) } let polygon = MKPolygon(coordinates: &coords, count: coords.count) mapView.addOverlay(polygon) counter = 0 } func mapView(mapView: MKMapView, annotationView view: MKAnnotationView, didChangeDragState newState: MKAnnotationViewDragState, fromOldState oldState: MKAnnotationViewDragState) { // if the user repositioned pin number2 then how to I update my array? } func mapView(mapView: MKMapView, rendererForOverlay overlay: MKOverlay) -> MKOverlayRenderer { if overlay is MKPolygon { let polygonView = MKPolygonRenderer(overlay: overlay) polygonView.strokeColor = UIColor.blackColor() polygonView.lineWidth = 0.5 return polygonView } return MKPolylineRenderer() } 

Answer 1

为了使引脚可拖动，您需要在MKAnnotationView上设置draggable = true 。 实现viewForAnnotation并出列或创build注释，然后设置draggable = true 。 确保MKMapView委托被设置，否则没有委托方法将被调用。

您也可能更容易将注释存储在数组中，而不是只存储坐标。 地图视图保留了对数组中注释的引用，所以当点在地图中移动时，注释会自动更新。

你的问题并没有说明你是否需要在点或点上划出一条路。 如果要绘制围绕点的叠加层，则还需要计算坐标的凸包。 代码示例这样做，虽然它很容易删除。

例：

 class MapAnnotationsOverlayViewController: UIViewController, MKMapViewDelegate { @IBOutlet var mapView: MKMapView! // Array of annotations - modified when the points are changed. var annotations = [MKPointAnnotation]() // Current polygon displayed in the overlay. var polygon: MKPolygon? override func viewDidLoad() { super.viewDidLoad() mapView.delegate = self addLongPressGesture() } func addLongPressGesture() { let longPressRecogniser = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress)) longPressRecogniser.minimumPressDuration = 0.25 mapView.addGestureRecognizer(longPressRecogniser) } func handleLongPress(gestureRecognizer: UIGestureRecognizer) { guard gestureRecognizer.state == .Began else { return } let touchPoint = gestureRecognizer.locationInView(self.mapView) let touchMapCoordinate = mapView.convertPoint(touchPoint, toCoordinateFromView: mapView) let annotation = MKPointAnnotation() // The annotation must have a title in order for it to be selectable. // Without a title the annotation is not selectable, and therefore not draggable. annotation.title = "Point \(annotations.count)" annotation.coordinate = touchMapCoordinate mapView.addAnnotation(annotation) // Add the new annotation to the list. annotations.append(annotation) // Redraw the overlay. updateOverlay() } @IBAction func drawAction(sender: AnyObject) { updateOverlay() } func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? { var view = mapView.dequeueReusableAnnotationViewWithIdentifier("pin") if let view = view { view.annotation = annotation } else { view = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "pin") // Allow the pin to be repositioned. view?.draggable = true } return view } func mapView(mapView: MKMapView, annotationView view: MKAnnotationView, didChangeDragState newState: MKAnnotationViewDragState, fromOldState oldState: MKAnnotationViewDragState) { // The map view retains a reference to the same annotations in the array. // The annotation in the array is automatically updated when the pin is moved. updateOverlay() } func updateOverlay() { // Remove existing overlay. if let polygon = self.polygon { mapView.removeOverlay(polygon) } self.polygon = nil if annotations.count < 3 { print("Not enough coordinates") return } // Create coordinates for new overlay. let coordinates = annotations.map({ $0.coordinate }) // Sort the coordinates to create a path surrounding the points. // Remove this if you only want to draw lines between the points. var hull = sortConvex(coordinates) let polygon = MKPolygon(coordinates: &hull, count: hull.count) mapView.addOverlay(polygon) self.polygon = polygon } func mapView(mapView: MKMapView, rendererForOverlay overlay: MKOverlay) -> MKOverlayRenderer { if overlay is MKPolygon { let polygonView = MKPolygonRenderer(overlay: overlay) polygonView.strokeColor = UIColor.blackColor() polygonView.lineWidth = 0.5 return polygonView } return MKPolylineRenderer() } } 

下面是凸包sortingalgorithm（从GitHub上的Gist改编而来）。

 func sortConvex(input: [CLLocationCoordinate2D]) -> [CLLocationCoordinate2D] { // X = longitude // Y = latitude // 2D cross product of OA and OB vectors, ie z-component of their 3D cross product. // Returns a positive value, if OAB makes a counter-clockwise turn, // negative for clockwise turn, and zero if the points are collinear. func cross(P: CLLocationCoordinate2D, _ A: CLLocationCoordinate2D, _ B: CLLocationCoordinate2D) -> Double { let part1 = (A.longitude - P.longitude) * (B.latitude - P.latitude) let part2 = (A.latitude - P.latitude) * (B.longitude - P.longitude) return part1 - part2; } // Sort points lexicographically let points = input.sort() { $0.longitude == $1.longitude ? $0.latitude < $1.latitude : $0.longitude < $1.longitude } // Build the lower hull var lower: [CLLocationCoordinate2D] = [] for p in points { while lower.count >= 2 && cross(lower[lower.count-2], lower[lower.count-1], p) <= 0 { lower.removeLast() } lower.append(p) } // Build upper hull var upper: [CLLocationCoordinate2D] = [] for p in points.reverse() { while upper.count >= 2 && cross(upper[upper.count-2], upper[upper.count-1], p) <= 0 { upper.removeLast() } upper.append(p) } // Last point of upper list is omitted because it is repeated at the // beginning of the lower list. upper.removeLast() // Concatenation of the lower and upper hulls gives the convex hull. return (upper + lower) } 

这是如何看起来与凸包sorting（围绕点绘制的path）：

这就是它没有sorting的样子（从点到点依次绘制的path）：