How to populate longitude latitude from JSON file into array - ios

Question

I need to find the nearest cities around my current location. Would you advice me how should I populate the coordinates into an array in my project and how to calculate the distance between my location and the nearest around me. I have to display the distance in (KM) and the city name ,so that the user can choose which city best fits for him.I also need to call the coordinates and the names in my code from a json file
My JSON File is:
{
"City A": {
"Position": {
"Longitude": 9.96233,
"Latitude": 49.80404
}
},
"City B": {
"Position": {
"Longitude": 6.11499,
"Latitude": 50.76891
}
},
"City C": {
"Position": {
"Longitude": 6.80592,
"Latitude": 51.53548
}
and my function so far:
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let userlocation:CLLocation = locations[0] as CLLocation
manager.stopUpdatingLocation()
let location = CLLocationCoordinate2D(latitude: userlocation.coordinate.latitude, longitude: userlocation.coordinate.longitude)
let span = MKCoordinateSpanMake(0.5, 0.5)
let region = MKCoordinateRegion(center: location, span: span)
Mapview.setRegion(region, animated: true)
let locations = ["42.6977,23.3219","43.6977,24.3219"]
let distanceMeters = userlocation.distanceFromLocation(CLLocation(latitude: 42.6977,longitude: 23.3219))
let distanceKilometers = distanceMeters / 1000.00
let roundedDistanceKilometers = String(Double(round(100 * distanceKilometers) / 100)) + " km"
// var distanceMeter = NSString(format: "\(distanceKilometers)km")

Answer 1

Assuming the JSON file is in the application bundle and is named cities.json first create a custom struct City
struct City {
let name : String
let location : CLLocation
}
Then in your controller declare an array cities
var cities = [City]()
To populate the array deserialize the JSON and extract the data
guard let url = NSBundle.mainBundle().URLForResource("cities", withExtension: "json"), jsonData = NSData(contentsOfURL: url) else { return }
do {
let jsonObject = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as! [String:AnyObject]
for (cityName, position) in jsonObject {
let coordinates = position["Position"] as! [String:CLLocationDegrees]
let longitude = coordinates["Longitude"]!
let latitude = coordinates["Latitude"]!
let location = CLLocation(latitude: latitude,longitude: longitude)
let city = City(name: cityName, location: location)
cities.append(city)
// print(cities)
}
} catch let error as NSError {
print(error)
}
To find the nearest location you could sort the array by distance
let nearestCity = cities.sort({ userLocation.distanceFromLocation($0.location) < userLocation.distanceFromLocation($1.location) }).first