ios - 如何在按钮func中传递特定func常数的值以将其用作导航的目的地

我如何在此函数中使用常量

func didSelect(place:QPlace) {

    guard let coordinates = place.location  else {
        return
    }

    // clear current marker
    marker?.map = nil

    // add marker
    marker = GMSMarker()
    marker?.position = coordinates
    marker?.title = place.name
    marker?.map = mapView
    mapView.selectedMarker = marker
    moveToMarker(marker!)

    // update bottom info panel view
    let desc = place.getDescription()
    descriptionLabel.text = desc.characters.count > 0 ? desc : "-"
    distanceLabel.text = "-"

    // update distance
    if userLocation != nil {
        let dist = distance(from: userLocation!, to: coordinates)
        distanceLabel.text = String.init(format: "Distance %.2f meters", dist)
        self.drawPath(startLocation: userLocation!, endLocation: coordinates)
    }

    title = place.name
}

（因此为coordinates常量）以在此处获取目标

  @IBAction func navigationStart(_ sender: Any) {

  let coordinate = CLLocationCoordinate2DMake(51.5007, -0.1246)
    let placeMark = MKPlacemark(coordinate: coordinate)
    let mapItem = MKMapItem(placemark: placeMark)
    mapItem.name = "Big Ben"
    mapItem.openInMaps(launchOptions: [MKLaunchOptionsDirectionsModeKey: MKLaunchOptionsDirectionsModeDriving])

}

我在点击按钮后在哪里打开地图，所以我想让坐标=坐标，我该怎么办？

最佳答案

基本上，您似乎想要保留对传入位置的引用，并在以后使用。这表明：


创建一个实例变量var destination: CLLocationCoordinate2D?
从方法分配目的地：

func didSelect(place:QPlace) {
    destination = place.location
}

设定目的地

@IBAction func navigationStart(_ sender: Any) {
    if let coordinate = self.destination {
        let placeMark = MKPlacemark(coordinate: coordinate)
        let mapItem = MKMapItem(placemark: placeMark)
        mapItem.name = "Big Ben"
        mapItem.openInMaps(launchOptions:
            [MKLaunchOptionsDirectionsModeKey:
            MKLaunchOptionsDirectionsModeDriving])
    }
}

我假设您的代码基于您的代码。没有检查类型。如果不起作用，那应该很容易解决。但主要逻辑是这样。

更新2：

func didSelect(place:QPlace) {
    guard let coordinates = place.location  else {
        return
    }
    // ADD THIS
    self.destination = coordinates

    // clear current marker
    marker?.map = nil

    // add marker
    marker = GMSMarker()
    marker?.position = coordinates
    marker?.title = place.name
    marker?.map = mapView
    mapView.selectedMarker = marker
    moveToMarker(marker!)

    // update bottom info panel view
    let desc = place.getDescription()
    descriptionLabel.text = desc.characters.count > 0 ? desc : "-"
    distanceLabel.text = "-"

    // update distance
    if userLocation != nil {
        let dist = distance(from: userLocation!, to: coordinates)
        distanceLabel.text = String.init(format: "Distance %.2f meters", dist)
        self.drawPath(startLocation: userLocation!, endLocation: coordinates)
    }

    title = place.name
}

关于ios - 如何在按钮func中传递特定func常数的值以将其用作导航的目的地，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/47141138/