ios - 局部变量不会复制到全局变量(swift)

Question

我需要将函数closestMarker()中的局部变量元组(sortedMarkers)复制到全局变量sortedMarkerGlobal中，但到目前为止它似乎不起作用。我想在另一个函数中使用sortedMarkersGlobal，但它的计数为零(空)。

class MapViewController: UIViewController {

@IBOutlet weak var mapView: GMSMapView!

var sortedMarkerGlobal: [(lat: String, long: String)] = []
var nextParkCount: Int = 1 // Used to iterate over sortedMarkers with nextPark IBAction button

let locationManager = CLLocationManager()
var lastLocation: CLLocation? = nil // Create internal value to store location from didUpdateLocation to use in func showDirection()
var isAnimating: Bool = false
var dropDownViewIsDisplayed: Bool = false

override func viewDidLoad() {
    super.viewDidLoad()
 ....
}

func closestMarker(userLat: Double, userLong: Double)-> [(lat: String, long: String)] {

    /*
    var lengthRow = firstRow.count

    while (sortedMarkers.count != lengthRow) { // There are markers that haven't been added to sortedMarkers
    // Haversine formula
    // add nearest marker to sortedMarkers
    // Remove recently added marker from ParseViewControler() type tuple
    // Recurse until all markers are in sortedMarkers
    }
    */

    let markerToTest = ParseViewController()
    let firstRow = markerToTest.returnParse()
    let lat2 = degreesToRadians(userLat) // Nearest lat in radians
    let long2 = degreesToRadians(userLong) // Nearest long in radians

    let R = (6371).doubleValue // Radius of earth in km

    var closestLat: Double? = nil // Used to store the latitude of the closest marker
    var closestLong: Double? = nil // Used to store the longitude of the closest marker

    //
    var indexToDelete: Int = 0 // Used to delete the marker which has been added to sortedMarkers tuple
    let lengthRow = firstRow.count
    var latLongs: (String, String)
    var sortedMarkers: [(lat: String, long: String)] = []

    var dynamicRow = firstRow // Tuple that has markers deleted from it

    while (sortedMarkers.count != lengthRow) { // Store markers from closest to furtherst distance from user
                var shortestDistance = 100.00E100
        for (var i = 0; i < dynamicRow.count; i++) {
                let testMarker = dynamicRow[i]
                let testLat = (testMarker.lat as NSString)
                let testLong = (testMarker.long as NSString)
                let doubleLat = Double(testLat as String)
                let doubleLong = Double(testLong as String)
                let lat1 = degreesToRadians(doubleLat!)
                let long1 = degreesToRadians(doubleLong!)

                let dLat = lat2 - lat1
                let dLong = long2 - long1

                let a = ((sin((dLat)/2)) * (sin((dLat)/2))) + (cos(lat1)*cos(lat2)*((sin((dLong)/2)) * (sin((dLong)/2))))
                let b = sqrt(a)
                let d = (2*R) * (asin(b)) // Haversine formula
                if (d < shortestDistance) {
                    closestLat = (doubleLat)
                    closestLong = (doubleLong)
                    shortestDistance = d
                    indexToDelete = i// Keep updating index of closest marker to later be removed
                }
            }
        latLongs = (String(closestLat!), String(closestLong!)) // Each time for loop will find closest marker ~ NOT WORKING ~
        sortedMarkers.append(latLongs)
        dynamicRow.removeAtIndex(indexToDelete) // Remove marker that has just been added
    }
    sortedMarkerGlobal = sortedMarkers
    return sortedMarkers
}

Answer 1

sortedMarkerGlobal 不是全局变量。目前它是一个实例变量，就像您定义的任何其他变量(locationManager、lastLocation、isAnimating 等)一样。

如果您希望它成为全局变量，您应该在类 MapViewController 之外定义它。

另一种选择是将其定义为 MapViewController 的类变量:

class MapViewController: UIViewController {
    static var sortedMarkerGlobal: [(lat: String, long: String)] = []
}