ios - 如何在按钮函数中传递特定函数的常量值以将其用作导航目的地

Question

如何在这个函数中使用常量

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
}

(因此常量坐标)在此处获取目的地

  @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])

}

我在点击按钮后打开 map ，所以我想让坐标=坐标，我该怎么办？

Answer 1

基本上，您似乎想保存对传入位置的引用并在以后使用它。这表明:

1. 创建实例变量var目标:CLLocationCooperative2D？

2. 从方法中指定目的地:

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

3. 设置目的地

   @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])
       }
   }
   

我基于你的代码假设它有效。没有检查类型。如果不起作用的话，这应该是一个简单的修复方法。但主要逻辑是这样的。

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
}