Locations in swift - swift

Question

I want to update the location when the user enters the app again. If a user opens the app you get correct data, but when you close the app (homebutton) and open it again it goes in the refresh function, but does not go in the location function. I can't get it. Here is my code:
import UIKit
import CoreLocation
var request : NSMutableURLRequest = NSMutableURLRequest()
class ViewController: UIViewController, CLLocationManagerDelegate {
let locationManager = CLLocationManager()
override func viewDidLoad() {
super.viewDidLoad()
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
}
func refresh(){
println("update")
locationManager.startUpdatingLocation()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated
}
func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!)
{
CLGeocoder().reverseGeocodeLocation(manager.location, completionHandler: {(placemarks, error)->Void in
if (error != nil)
{
println("Error: " + error.localizedDescription)
return
}
if (placemarks.count > 0)
{
let pm = placemarks[0] as! CLPlacemark
self.displayLocationInfo(pm)
}
else
{
println("Error with the data.")
}
})
}
in my app delegate i have this:
func applicationWillEnterForeground(application: UIApplication) {
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
ViewController().refresh();
}
So it goes in the refresh function, but than it does noting.. What can it be?
Thank you!

Answer 1

in each call of applicationWillEnterForeground(application: UIApplication) you create a new object of ViewController, call refresh() on it and let it go away. This is not the view controller object, that is presented to the user.
Instead you must get the presented ViewController object and call refresh() on it.
It could be something like
func applicationWillEnterForeground(application: UIApplication) {
let viewController= self.window.rootViewController as! ViewController
viewController.refresh()
}
But how it looks exactly, depends on details in your code we don't know.
or delete that line altogether and subrcribe for the WillEnterForeground notification in your ViewController's viewDidLoad()
override func viewDidLoad()
{
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: "applicationWillEnterForeground:", name: UIApplicationWillEnterForegroundNotification, object: nil)
}
func applicationWillEnterForeground(notification: NSNotification) {
self.refresh()
}
deinit {
NSNotificationCenter.defaultCenter().removeObserver(self)
}

Answer 2

The challenge you have is that when you press the home key, your views do not unload but are merely suspended. Therefore with this, the viewDidLoad method does not get called, when your application resumes...
What you are actually doing is dealing with the application coming into the foreground which you have to register to receive notifications about. Add the following line to your viewDidLoad method:
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("applicationWillEnterForeground"), name: UIApplicationWillEnterForegroundNotification, object: nil)
That will add an observer for the UIApplicationWillEnterForegroundNotification event and then call the method applicationWillEnterForeground. Now all you need to do is create the method applicationWillEnterForeground and call your refresh method from within it.