Local variable won't copy to global variable (swift) - ios

Question

I need to copy a local variable tuple (sortedMarkers) from the function closestMarker() into the global variable sortedMarkerGlobal, however it doesn't seem to be working thus far. I want to use sortedMarkersGlobal in another function but it's count is zero (empty).
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 is not a global variable. currently it is an instance variable like any of the other variables you have defined (locationManager, lastLocation, isAnimating, etc).
if you want it to be a global variable you should define it outside of your class MapViewController.
another option would be to make it a class variable of MapViewController by defining it as:
class MapViewController: UIViewController {
static var sortedMarkerGlobal: [(lat: String, long: String)] = []
}

Answer 2

Well I tried to test your code in playground and it worked for me
import UIKit
class Test {
var global:[(lat: String, long: String)] = []
func test1() {
var sortedMarkers: [(lat: String, long: String)] = []
var latLongs: (String, String)
latLongs = ("123", "123")
sortedMarkers.append(latLongs)
global = sortedMarkers
}
}
let test:Test = Test()
test.test1();
print("global \(test.global)")
And the result is global [("123", "123")] so I guess it should also work for you, the problem might be somewhere else.

Answer 3

I would suggest that you just use a closures instead of saving to a global variable. This lets you pass in the parameters and return your result based on that. You can save that result in the function that called it and do what ever you want from there.