swift - MapKit 中的长按

Question

我正在使用 Swift 3 构建应用。

一切似乎都工作正常，但是当我在 map 中长按时，它就像被长按两次一样。我不知道为什么...我在长压机内做了一个打印，以计算长压机，每次我长压机(一次)它都会检测到两次长压机……为什么会这样？有什么问题吗？

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

每次状态更改时都会调用选择器，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
}