Ios 在地图上重复pin注释

我刚开始学斯威夫特

问题:

当我触摸地图以放置pin注释并拖动手指时，它会创建注释的重复线

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Xcode 8.2•Swift 3.0.2

你只需要检查手势识别器的状态，如果没有，请确认。开始返回。只需在操作方法的顶部添加以下if条件：

func action(_ gestureRecognizer: UIGestureRecognizer) {

    if gestureRecognizer.state != UIGestureRecognizerState.began {
        return
    }

    //  your code

如果要允许用户在触摸时移动pin，则需要切换手势识别器状态，并在GestureRecognitor.state发生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")
    }
}

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")
    }
}