ios - 如何将值从一个函数传递到另一个函数？

Question

我想将我当前的位置坐标从 func locationManager() 传递到我的 func viewDidLoad() 我该如何传递它？

let manager = CLLocationManager()
var myLocation: CLLocationCoordinate2D?
var location=0
var latPass: Double!
var longPass: Double!

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
{
    var location=locations[0]
    let span:MKCoordinateSpan=MKCoordinateSpanMake(0.01, 0.01)
    var myLocation:CLLocationCoordinate2D=CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
    let region:MKCoordinateRegion=MKCoordinateRegionMake(myLocation, span)
    latPass=location.coordinate.latitude
    longPass=location.coordinate.longitude
}

当我在 func locationManager 中打印我的 lat 和 long 时，我得到了值，但是当我在我的 中打印它时viewDidLoad()，我得到 nil

这是我的 viewDidLoad()

override func viewDidLoad() {
    super.viewDidLoad()

    print(latPass)
    print(longPass)

    let position = CLLocationCoordinate2D(latitude:latPass, longitude: longPass)
    let london = GMSMarker(position: position)
    london.title = "You"
    london.tracksViewChanges=true
    london.icon = UIImage(named: "currentLocation.png")
    london.map = mapView
    mapView.selectedMarker=london
}

我想我必须创建一个 var 的实例，但我找不到方法。

Answer 1

ViewDidLoad 它是 View Controller 调用的第一个方法，一旦它被调用，其他方法也会被调用。您需要在 viewDidLOad 类中设置委托(delegate)。这些参数在加载 View 期间保持为空，但是当调用委托(delegate)方法时它将存储数据，您将按照方法中的方法获取它。

你需要这样:

override func viewDidLoad() {
    super.viewDidLoad()

    manager.delegate = self
}

然后这个方法执行它的东西:

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
{
    var location=locations[0]
    let span:MKCoordinateSpan=MKCoordinateSpanMake(0.01, 0.01)
    var myLocation:CLLocationCoordinate2D=CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
    let region:MKCoordinateRegion=MKCoordinateRegionMake(myLocation, span)
    latPass=location.coordinate.latitude
    longPass=location.coordinate.longitude
    print(latPass)
    print(longPass)
    /// Here you can set the positioning managing stuff, because lat long are showing.
   let position = CLLocationCoordinate2D(latitude:latPass, longitude: longPass)
   let london = GMSMarker(position: position)
   london.title = "You"
   london.tracksViewChanges=true
   london.icon = UIImage(named: "currentLocation.png")
   london.map = mapView
   mapView.selectedMarker=london
}

调用方法后，您可以看到输出的控制台。