Xcode GPS location manager access message - iphone

Question

How can I do the following please?
I have a button in my iPhone app that the user clicks to start GPS navigation. All I do when the button is clicked is get their location, and pass it to Google maps to do the rest.
However, as soon as I land on the screen where the button is, the application ask me the standard "This app would like to use your current location". But I dont want this to be asked as soon as I land on the screen. Instead, it should be asked when the button is clicked.
Here is how I handle the scenario in my views .m file:
- (void)viewDidLoad
{
self.locationManager = [[CLLocationManager alloc] init];
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.delegate = self;
[locationManager startUpdatingLocation];
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
And then when the button is clicked. Also tried to put the code from viewDidLoad here as can be seen from the commented out section. This works in that I dont get asked the question when the view loads, but then the GPS does not work once button is clicked. I get an error message on the app screen saying "The app was unable to establish a route to the nearest road". And the "This app would like to access your current location" only flashes up on the screen briefly.
- (IBAction)gpsNavigation:(id)sender
{
/*
self.locationManager = [[CLLocationManager alloc] init];
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.delegate = self;
[locationManager startUpdatingLocation];
*/
NSString *destAddress = #"52.269444, -9.708674";
NSString *url = [NSString stringWithFormat: #"http://maps.apple.com/maps?saddr=%f%f&daddr=%#",
locationManager.location.coordinate.latitude,
locationManager.location.coordinate.longitude,
[destAddress stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:url]];
}

Answer 1

Please use commented code in gpsNavigation: method.
Your problem is that you get locationManager.location as soon as you call [locationManager startUpdatingLocation].
So your code can be as following.
- (IBAction)gpsNavigation:(id)sender
{
self.locationManager = [[CLLocationManager alloc] init];
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.delegate = self;
[locationManager startUpdatingLocation];
}
- (void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSString *destAddress = #"52.269444, -9.708674";
NSString *url = [NSString stringWithFormat: #"http://maps.apple.com/maps?saddr=%f%f&daddr=%#",
locationManager.location.coordinate.latitude,
locationManager.location.coordinate.longitude,
[destAddress stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:url]];
[locationManager stopUpdatingLocation];
}

Answer 2

As soon as you call [locationManager startUpdatingLocation] your app request locations and will ask the user for permission. So delay this call untill you need it (button pressed)