Loop through coordinates and find the closest shop to a point Swift 3 - ios

Question

Idea :
App lets drivers see the closest shop/restaurants to customers.
What I have :
Coordinates saved as strings
let clientLat = "24.449384"
let clientLng = "56.343243"
a function to find all the shops in my local area
I tried to save all the coordinates of a shop in my local area and I succeeded:
var coordinates: [CLLocationCoordinate2D] = [CLLocationCoordinate2D]()
func performSearch() {
coordinates.removeAll()
let request = MKLocalSearchRequest()
request.naturalLanguageQuery = "starbucks"
request.region = mapView.region
let search = MKLocalSearch(request: request)
search.start(completionHandler: {(response, error) in
if error != nil {
print("Error occured in search: \(error!.localizedDescription)")
} else if response!.mapItems.count == 0 {
print("No matches found")
} else {
print("Matches found")
for item in response!.mapItems {
self.coordinates.append(item.placemark.coordinate)
// need to sort coordinates
// need to find the closest
let annotation = MKPointAnnotation()
annotation.coordinate = item.placemark.coordinate
annotation.title = item.name
self.mapView.addAnnotation(annotation)
}
}
})
}
What I need:
I wish to loop through the coordinates and find the closest shop (kilometers) to the lat and long strings then put a pin on it.
UPDATE
func performSearch() {
coordinates.removeAll()
let request = MKLocalSearchRequest()
request.naturalLanguageQuery = "starbucks"
request.region = mapView.region
let search = MKLocalSearch(request: request)
search.start(completionHandler: {(response, error) in
if error != nil {
print("Error occured in search: \(error!.localizedDescription)")
} else if response!.mapItems.count == 0 {
print("No matches found")
} else {
print("Matches found")
for item in response!.mapItems {
self.coordinates.append(item.placemark.coordinate)
let pointToCompare = CLLocation(latitude: 24.741721, longitude: 46.891440)
let storedCorrdinates = self.coordinates.map({CLLocation(latitude: $0.latitude, longitude: $0.longitude)}).sorted(by: {
$0.distance(from: pointToCompare) < $1.distance(from: pointToCompare)
})
self.coordinate = storedCorrdinates
}
let annotation = MKPointAnnotation()
annotation.coordinate = self.coordinate[0].coordinate
self.mapView.addAnnotation(annotation)
}
})
}
Thank you #brimstone

Answer 1

You can compare distances between coordinates by converting them to CLLocation types and then using the distance(from:) method. For example, take your coordinates array and map it to CLLocation, then sort that based on the distance from the point you are comparing them to.
let coordinates = [CLLocationCoordinate2D]()
let pointToCompare = CLLocation(latitude: <#yourLat#>, longitude: <#yourLong#>)
let sortedCoordinates = coordinates.map({CLLocation(latitude: $0.latitude, longitude: $0.longitude)}).sorted(by: {
$0.distance(from: pointToCompare) < $1.distance(from: pointToCompare)
})
Then, to set your annotation's coordinate to the nearest coordinate, just subscript the sortedCoordinates array.
annotation.coordinate = sortedCoordinates[0].coordinate

Answer 2

I would like to share my solution :)
1) In my case, I upload data from the API, so I need to create a model.
import MapKit
struct StoresMap: Codable {
let id: Int?
let title: String?
let latitude: Double?
let longitude: Double?
let schedule: String?
let phone: String?
let ukmStoreId: Int?
var distanceToUser: CLLocationDistance?
}
The last variable is not from API, but from myself to define distance for each store.
2) In ViewController I define:
func fetchStoresList() {
NetworkManager.downloadStoresListForMap(firstPartURL: backendURL) { (storesList) in
self.shopList = storesList
let initialLocation = self.locationManager.location!
for i in 0..<self.shopList.count {
self.shopList[i].distanceToUser = initialLocation.distance(from: CLLocation(latitude: self.shopList[i].latitude!, longitude: self.shopList[i].longitude!))
}
self.shopList.sort(by: { $0.distanceToUser! < $1.distanceToUser!})
print("Closest shop - ", self.shopList[0])
}
}
3) Don't forget to call the function in viewDidLoad() and import MapView framework :)