iOS Mapkit 注释无法拖动

Question

我是 iOS 开发新手，需要在 iOS 地图中实现可拖动注释。我的代码如下。无论我做什么，我都无法获得可拖动的注释，之后我需要获取引脚指向的位置的地址，任何人都可以帮助注释

RegistrationViewController.swift

class RegistrationViewController: UIViewController,UIPickerViewDelegate,UIPickerViewDataSource,MKMapViewDelegate{
    @IBOutlet weak var mapView: MKMapView!

    override func viewDidLoad() {
        super.viewDidLoad()
        var centerLocation = CLLocationCoordinate2DMake(12.964370125970357, 77.59643554937497)
        var mapspan = MKCoordinateSpanMake(0.01, 0.01)
        var mapregion = MKCoordinateRegionMake(centerLocation, mapspan)
        self.mapView.setRegion(mapregion, animated: true)

        let pin = pinAnnotation(title:"hello",subtitle:"how are you",coordinate:centerLocation)
        mapView.addAnnotation(pin)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
        if annotation is MKPointAnnotation {
            let pinAnnotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "myPin")
            pinAnnotationView.pinColor = .purple
            pinAnnotationView.isDraggable = true
            pinAnnotationView.canShowCallout = true
            pinAnnotationView.animatesDrop = true

            return pinAnnotationView
        }

        return nil
    }

    func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, didChange newState: MKAnnotationViewDragState, fromOldState oldState: MKAnnotationViewDragState) {
        switch newState {
        case .starting:
            view.dragState = .dragging
        case .ending, .canceling:
            view.dragState = .none
        default: break
        }
    }

pinAnnotation.swift

import MapKit

class pinAnnotation:NSObject,MKAnnotation {
    var title:String?
    var subtitle: String?
    var coordinate: CLLocationCoordinate2D
    init(title:String,subtitle:String,coordinate:CLLocationCoordinate2D) {
        self.title = title
        self.subtitle = subtitle
        self.coordinate = coordinate
    }
}

Answer 1

在你的情况下annotation不是一种MKPointAnnotation类型。这就是为什么它没有进入if annotation is MKPointAnnotation {状态。

它应该是这样的：

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

    if annotation is pinAnnotation {

        let pinAnnotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "myPin")
        pinAnnotationView.pinTintColor = .purple
        pinAnnotationView.isDraggable = true
        pinAnnotationView.canShowCallout = true
        pinAnnotationView.animatesDrop = true

        return pinAnnotationView
    }

    return nil
}

因为annotation是pinAnnotation类型。

mapView.delegate = self我在你的代码中看不到。但是，如果您通过故事板分配它，那就没问题，否则将其添加到viewDidLoad方法中。

你的完整代码将是：

import UIKit
import MapKit

class ViewController: UIViewController,MKMapViewDelegate{
    @IBOutlet weak var mapView: MKMapView!


    override func viewDidLoad() {
        super.viewDidLoad()
        mapView.delegate  = self
        let centerLocation = CLLocationCoordinate2D(latitude: 12.964370125970357, longitude: 77.59643554937497)
        let mapspan = MKCoordinateSpanMake(0.01, 0.01)
        let mapregion = MKCoordinateRegionMake(centerLocation, mapspan)
        self.mapView.setRegion(mapregion, animated: true)

        let pin = pinAnnotation(title:"hello",subtitle:"how are you",coordinate:centerLocation)
        mapView.addAnnotation(pin)

    }


    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

        if annotation is pinAnnotation {

            let pinAnnotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "myPin")
            pinAnnotationView.pinTintColor = .purple
            pinAnnotationView.isDraggable = true
            pinAnnotationView.canShowCallout = true
            pinAnnotationView.animatesDrop = true

            return pinAnnotationView
        }

        return nil
    }

    func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, didChange newState: MKAnnotationViewDragState, fromOldState oldState: MKAnnotationViewDragState) {
        switch newState {
        case .starting:
            view.dragState = .dragging
        case .ending, .canceling:
            view.dragState = .none
        default: break
        }
    }
}

编辑

您可以通过以下方式获取新位置view.annotation?.coordinate

检查下面的代码：

func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, didChange newState: MKAnnotationViewDragState, fromOldState oldState: MKAnnotationViewDragState) {
    switch newState {
    case .starting:
        view.dragState = .dragging
    case .ending, .canceling:
        //New cordinates
        print(view.annotation?.coordinate)
        view.dragState = .none
    default: break
    }
}