Swift Location Distance Demo

LocationService.swift

import CoreLocation

struct Venue {
	
	var name: String
	var location: CLLocation
	
	init(name: String, lat: Double, lng: Double) {
		self.name = name
		self.location = CLLocation(latitude: lat, longitude: lng)
	}
	
}

class LocationsService {
	
	var locations: Array<Venue>
	
	init() {
		locations = []
		
		locations.append(Venue(name: "New York", lat: 40.712775, lng: -74.005973))
		locations.append(Venue(name: "Manhattan", lat: 40.78306, lng: -73.971249))
		locations.append(Venue(name: "Brooklyn", lat: 40.678178, lng: -73.944158))
		locations.append(Venue(name: "San Francisco", lat: 37.77493, lng: -122.419415))
		locations.append(Venue(name: "Bayview Opera House", lat: 37.735187, lng: -122.390002))
		
		// ... 
		// add more locations to demo
		// get geo-codes from https://developers.google.com/maps/documentation/javascript/examples/geocoding-simple
	}
	
	// this method is used to demonstrate filtering a lot of geo-locations based on a given lat,lng and a radius
	// often this will be a query to a backend server, and the backend will do the filtering using a more efficient formula
	// for this demo, we use a list of known locations in memory. The backend will often return the distance 
	func getLocations(lat: Double, lng: Double, radius: Double) -> Array<Venue> {
		
		let radiusInMeters = radius * 1000
		let userLocation = CLLocation(latitude: lat, longitude: lng)
		
		var response = [Venue]()
		
		if (locations.count > 0) {
			for i in locations {
				// you may also return the distance from current location, so it can be used for sorting
				// sorting is not included in this demo
				if (i.location.distance(from: userLocation) < radiusInMeters) {
					response.append(i)
				}
			}
		}
			
		return response
	}
	
}

let locationsService = LocationsService()

// here we give the user's starting location. Usually the user's current geo-location
// the radius is given in km. This will filter the locations with a given raidus.
// var locations = locationsService.getLocations(lat: 40.712775, lng: -74.005973, radius: 500)

// usage demo

// get locations closer to New York
print("Locations closer to New York")
var locations = locationsService.getLocations(lat: 40.712775, lng: -74.005973, radius: 500)
if (locations.count > 0) {
	for i in locations {
		print(i.name)
	}
	
	} else {
	print("No Locations found")
}

// get locations closer to San Francisco
print("Locations closer to San Francisco")
locations = locationsService.getLocations(lat: 37, lng: -122, radius: 500)
if (locations.count > 0) {
	for i in locations {
		print(i.name)
	}
	
	} else {
	print("No Locations found")
}