I'm trying to build my first Swift application. In this application I'm looping over an KML file that contains information about some restaurant and for each one of them I'm trying to build a Place
object with the available information, compare a distance and keep the Place
which is the closest to a given point.
Here is my Place model, a very simple model (Place.swift):
import Foundation
import MapKit
class Place {
var name:String
var description:String? = nil
var location:CLLocationCoordinate2D = CLLocationCoordinate2D(latitude:0, longitude:0)
init(name: String, description: String?, latitude: Double, longitude: Double)
{
self.name = name
self.description = description
self.location = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
}
func getDistance(point: CLLocationCoordinate2D) -> Float
{
return Geo.distance(point, coordTo: self.location)
}
}
and here is the part of the application that is looping over the items from the KML file.
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {(response, data, error) in
let xml = SWXMLHash.parse(data);
var minDistance:Float = Float(UInt64.max)
var closestPlace:Place? = nil
var place:Place? = nil
for placemark in xml["kml"]["Document"]["Folder"]["Placemark"] {
var coord = placemark["Point"]["coordinates"].element?.text?.componentsSeparatedByString(",")
// Create a place object if the place has a name
if let placeName = placemark["name"].element?.text {
NSLog("Place name defined, object created")
// Overwrite the place variable with a new object
place = Place(name: placeName, description: placemark["description"].element?.text, latitude: (coord![1] as NSString).doubleValue, longitude: (coord![0] as NSString).doubleValue)
var distance = place!.getDistance(self.middlePosition)
if distance < minDistance {
minDistance = distance
closestPlace = place
} else {
NSLog("Place name could not be found, skipped")
}
}
}
I added breakpoints in this script, when the distance is calculated. The value of the place
variable is nil and I don't understand why. If I replace this line:
place = Place(name: placeName, description: placemark["description"].element?.text, latitude: (coord![1] as NSString).doubleValue, longitude: (coord![0] as NSString).doubleValue)
by this line:
let place = Place(name: placeName, description: placemark["description"].element?.text, latitude: (coord![1] as NSString).doubleValue, longitude: (coord![0] as NSString).doubleValue)
I can see that my place object is instantiated correctly now but I can't understand why. Also I have the exact same issue when I tried to save the closest place:
closestPlace = place
In the inspector the value of closestPlace
is nil even after being set with my place object.
I fixed my issue adding a !
after the Place
object. I guess is to tell that I am sure I have an Object in this variable and that is not nil.
if let placeName = placemark["name"].element?.text {
NSLog("Place name defined, object created")
// Overwrite the place variable with a new object
place = Place(name: placeName, description: placemark["description"].element?.text, latitude: (coord![1] as NSString).doubleValue, longitude: (coord![0] as NSString).doubleValue)
var distance = place!.getDistance(self.middlePosition)
if distance < minDistance {
minDistance = distance
closestPlace = place!
} else {
NSLog("Place name could not be found, skipped")
}
}