Question

我在Swift 3中建立一个应用程序。

所有接缝都能正常工作但是当我在地图中长按时，它会像是长按两次一样。我不知道为什么...... 我在长按里面做了一个打印，计算了长按，每次我长按（一次）都会检测到两个长按...为什么会发生这种情况？这有什么不对吗？

import UIKit
import MapKit

class ViewController: UIViewController, MKMapViewDelegate {

@IBOutlet var map: MKMapView!

var numberOfLongPress : Int = 0

override func viewDidLoad() {
    super.viewDidLoad()


    let latitude: CLLocationDegrees = 38.925560

    let longitude: CLLocationDegrees = -9.229723

    let lanDelta: CLLocationDegrees = 0.05

    let lonDelta: CLLocationDegrees = 0.05

    let span = MKCoordinateSpan(latitudeDelta: lanDelta, longitudeDelta: lonDelta)

    let coordinates = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)

    let region = MKCoordinateRegion(center: coordinates, span: span)

    map.setRegion(region, animated: true)

    let lpgr = UILongPressGestureRecognizer(target: self, action: #selector(ViewController.longpress(gestureRecognizer:)))

    lpgr.minimumPressDuration = 0.5

    map.addGestureRecognizer(lpgr)

}

func longpress(gestureRecognizer: UIGestureRecognizer) {

    let touchPoint = gestureRecognizer.location(in: self.map)

    let coordinate = map.convert(touchPoint, toCoordinateFrom: self.map)

    let annotation = MKPointAnnotation()

    annotation.coordinate = coordinate

    annotation.title = "My Place"



    map.addAnnotation(annotation)

    print("longpress activated")

    numberOfLongPress = numberOfLongPress + 1

    print(numberOfLongPress) //detect number of long presses

}

}

Answer 1

每次状态更改都会调用选择器，因此您最好检查状态，并在.began或.ended上执行您需要执行的操作。

func longpress(gestureRecognizer: UIGestureRecognizer) {
    guard gestureRecognizer.state == .began else { return }

    // add annotation
}

Answer 2

让我们打印gestureRecognizer的状态，您会看到.began和.ended。因此，在添加注释之前，请检查gestureRecognizer的状态。

func longpress(gestureRecognizer: UILongPressGestureRecognizer) {
    if gestureRecognizer.state == began {
        // do something here
    }
}

MapKit中的LongPress

2 个答案: