alert controller not displaying in iphone using swift2 - ios

Question

in my app i want to use alert controller so am using the following code:
import UIKit
import CoreLocation
class GPSTrackingManager: NSObject,CLLocationManagerDelegate {
var locationManager: CLLocationManager!
var seenError : Bool = false
func startTracking() {
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestAlwaysAuthorization()
locationManager.startUpdatingLocation()
}
func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
locationManager.stopUpdatingLocation()
print("error occured:\(error)")
}
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
//println("locations = \(locationManager)")
let latValue = locationManager.location!.coordinate.latitude
let lonValue = locationManager.location!.coordinate.longitude
print(latValue)
print(lonValue)
GoogleLat = latValue
GoogleLong = lonValue
CLGeocoder().reverseGeocodeLocation(manager.location!, completionHandler: {(placemarks, error)->Void in
if (error != nil)
{
print("Reverse geocoder failed with error" + error!.localizedDescription)
return
}
if placemarks!.count > 0
{
let pm = placemarks![0] as CLPlacemark
self.displayLocationInfo(pm)
}
else
{
print("Problem with the data received from geocoder")
}
})
}
func displayLocationInfo(placemark: CLPlacemark?)
{
if let containsPlacemark = placemark
{
locationManager.stopUpdatingLocation()
let fourthcity = (containsPlacemark.subAdministrativeArea != nil) ? containsPlacemark.subAdministrativeArea : ""
let fourthState = (containsPlacemark.administrativeArea != nil) ? containsPlacemark.administrativeArea : ""
let fourthCountry = (containsPlacemark.country != nil) ? containsPlacemark.country : ""
print("my Real City = \(fourthcity)")
let fullName = fourthcity
let fullNameArr = fullName!.characters.split{$0 == " "}.map(String.init)
fullNameArr[0]
print(fullNameArr[0])
print("myState = \(fourthState)")
print("myCountry = \(fourthCountry)")
appDelCityname = fullNameArr[0]
appDelStateName = fourthState
appDelCountryName = fourthCountry
print("AppDelegate City Name = \(appDelCityname)")
}
}
func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
switch status {
case .NotDetermined:
// If status has not yet been determied, ask for authorization
manager.requestWhenInUseAuthorization()
break
case .AuthorizedWhenInUse:
// If authorized when in use
print("AuthorizedWhenInUse")
manager.startUpdatingLocation()
break
case .AuthorizedAlways:
// If always authorized
print("AuthorizedAlways")
manager.startUpdatingLocation()
break
case .Denied:
// If user denied your app access to Location Services, but can grant access from Settings.app
print("user denied to allow")
dispatch_async(dispatch_get_main_queue(), {
NSTimer.scheduledTimerWithTimeInterval(3.0,target: self, selector: #selector(self.DisplayalertToturnonLocation), userInfo: nil, repeats: false)
})
break
default:
print("user cant allow location service")
break
}
}
func DisplayalertToturnonLocation(){
let alertController = UIAlertController(title: "GPRS is Required", message: "This app requires your location,please turn on your location service or set your address", preferredStyle: .Alert)
let saveAction = UIAlertAction(title: "Set Address", style: UIAlertActionStyle.Default, handler: {
alert -> Void in
self.alertTogetAdrressFromUser()
})
alertController.addAction(saveAction)
let cancelAction = UIAlertAction(title: "Settings", style: UIAlertActionStyle.Default, handler: {
(action : UIAlertAction!) -> Void in
UIApplication.sharedApplication().openURL(NSURL(string: UIApplicationOpenSettingsURLString)!)
})
alertController.addAction(cancelAction)
let keyWindow = UIApplication.sharedApplication().keyWindow
let mainController = keyWindow!.rootViewController!
mainController.presentViewController(alertController, animated: true, completion: nil)
}
}
I am calling this function in AppDelegate which executes well in iPad but not in iPhone also it not shows any error or warning and am feeling too difficult to find what am doing wrong here so any one help me to display alert controller in iPhone.
in AppDelegate:
var tracking = GPSTrackingManager()
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
tracking.startTracking()
}

Answer 1

in here you need to follow two things . 1. your code is fine you need to show ur alertcontroller using main thread, else find the root wihch one is most top presnt your alert, else check once your current window is visible or not
present your UIAlertcontroller in Main thread, for e.g
Swift3
DispatchQueue.main.async {
self.tracking.DisplayalertToturnonLocation()
}
swift2
dispatch_async(dispatch_get_main_queue()) {
self.tracking.DisplayalertToturnonLocation()
}
you get the output as
full code
class GPSTrackingManager: NSObject {
func DisplayalertToturnonLocation(){
let alertController = UIAlertController(title: "GPRS is Required", message: "This app requires your location,please turn on your location service or set your address", preferredStyle: .alert)
let saveAction = UIAlertAction(title: "Set Address", style: UIAlertActionStyle.default, handler: {
alert -> Void in
// self.alertTogetAdrressFromUser()
})
alertController.addAction(saveAction)
let cancelAction = UIAlertAction(title: "Settings", style: UIAlertActionStyle.default, handler: {
(action : UIAlertAction!) -> Void in
// UIApplication.shared.openURL(NSURL(string: UIApplicationOpenSettingsURLString)! as URL)
})
alertController.addAction(cancelAction)
UIApplication.shared.keyWindow?.rootViewController?.present(alertController, animated: true, completion: nil)
}
}