在地图上重复引脚注释

我刚刚开始学习Swift。

题：

当我在地图上触摸放置引脚注释并拖动我的手指时，会创build重复的注释行。

import UIKit import MapKit import CoreLocation class ViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate { @IBOutlet weak var map: MKMapView! var manager:CLLocationManager! override func viewDidLoad() { super.viewDidLoad() //Manager for current location manager = CLLocationManager() manager.delegate = self manager.desiredAccuracy = kCLLocationAccuracyBest manager.requestWhenInUseAuthorization() manager.startUpdatingLocation() //Getting touch Gesture to add bookmark let uilpgr = UILongPressGestureRecognizer(target: self, action: "action:") uilpgr.minimumPressDuration = 1 uilpgr.numberOfTouchesRequired = 1 map.addGestureRecognizer(uilpgr) } func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { let userLocation:CLLocation = locations[0] let latitude:CLLocationDegrees = userLocation.coordinate.latitude let longitude:CLLocationDegrees = userLocation.coordinate.longitude let latDelta:CLLocationDegrees = 0.002 let lonDelta:CLLocationDegrees = 0.002 let span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, lonDelta) let location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude) let region:MKCoordinateRegion = MKCoordinateRegionMake(location, span) map.setRegion(region, animated: true) } func action(gestureRecognizer: UIGestureRecognizer) { let touchPoint = gestureRecognizer.locationInView(self.map) let newCoordinate: CLLocationCoordinate2D = map.convertPoint(touchPoint, toCoordinateFromView: self.map) print(newCoordinate) let annotation = MKPointAnnotation() annotation.coordinate = newCoordinate annotation.title = "New Place" annotation.subtitle = "One day I'll go here..." map.addAnnotation(annotation) } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } } 

Answer 1

Xcode 8.2•Swift 3.0.2

你只需要检查手势识别器的状态，并确保没有。开始返回。 只要在动作方法的顶部添加这个条件即可：

 func action(_ gestureRecognizer: UIGestureRecognizer) { if gestureRecognizer.state != UIGestureRecognizerState.began { return } // your code 

如果您希望允许用户在触摸的同时移动引脚，则需要切换手势识别器状态并在gestureRecognizer.state更改时更新注释坐标：

 func action(_ gestureRecognizer: UIGestureRecognizer) { switch gestureRecognizer.state { case .began: let annotation = MKPointAnnotation() annotation.coordinate = mapView.convert(gestureRecognizer.location(in: mapView), toCoordinateFrom: mapView) annotation.title = "Untitled" mapView.addAnnotation(annotation) case .changed: if let annotation = (mapView.annotations.filter{$0.title! == "Untitled" }).first as? MKPointAnnotation { annotation.coordinate = mapView.convert(gestureRecognizer.location(in: mapView), toCoordinateFrom: mapView) } case .cancelled: if let annotation = (mapView.annotations.filter{$0.title! == "Untitled" }).first as? MKPointAnnotation { mapView.removeAnnotation(annotation) } // you can also prompt the user here for the annotation title case .ended: if let annotation = (mapView.annotations.filter{$0.title! == "Untitled" }).first as? MKPointAnnotation { let alert = UIAlertController(title: "New Annotation", message: "", preferredStyle: .alert) var inputTextField: UITextField? alert.addAction(UIAlertAction(title: "Add", style: .default) { _ in if let annotationTitle = inputTextField?.text { annotation.title = annotationTitle annotation.subtitle = "Lat:\(String(format: "%.06f", annotation.coordinate.latitude)) Lon:\(String(format: "%.06f", annotation.coordinate.longitude))" } }) alert.addTextField(configurationHandler: { textField in textField.placeholder = "Place Description" inputTextField = textField }) alert.addAction(UIAlertAction(title: "Cancel", style: .cancel){ _ in self.mapView.removeAnnotation(annotation) }) present(alert, animated: true, completion: nil) } default: print("default") } }