iOS: App is not asking user's permission while installing the app. getting kCLAuthorizationStatusNotDetermined every time - Objective-c & Swift

I am trying to fetch user location in my iOS app. I have included corelocation framework in my project first. Then on a button click I am invoking the core location api as below. When I am trying to install this in a device, the core location never asks the user permission. When I try to fetch the location on button click, I am getting kCLAuthorizationStatusNotDetermined as the authorisationStatus. Please help me in this. I have no clue what is happening.

- (IBAction)fetchLessAccurateLocation:(id)sender {
    [self.txtLocation setText:@""];

    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
    locationManager.distanceFilter = 1000;

    if ([self shouldFetchUserLocation]) {
        [locationManager startUpdatingLocation];
    }
}

This is my shouldFetchUserLocation method:

-(BOOL)shouldFetchUserLocation{

    BOOL shouldFetchLocation= NO;

    if ([CLLocationManager locationServicesEnabled]) {
        switch ([CLLocationManager authorizationStatus]) {
            case kCLAuthorizationStatusAuthorized:
                shouldFetchLocation= YES;
                break;
            case kCLAuthorizationStatusDenied:
            {
                UIAlertView *alert= [[UIAlertView alloc]initWithTitle:@"Error" message:@"App level settings has been denied" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                [alert show];
                alert= nil;
            }
                break;
            case kCLAuthorizationStatusNotDetermined:
            {
                UIAlertView *alert= [[UIAlertView alloc]initWithTitle:@"Error" message:@"The user is yet to provide the permission" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                [alert show];
                alert= nil;
            }
                break;
            case kCLAuthorizationStatusRestricted:
            {
                UIAlertView *alert= [[UIAlertView alloc]initWithTitle:@"Error" message:@"The app is recstricted from using location services." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                [alert show];
                alert= nil;
            }
                break;

            default:
                break;
        }
    }
    else{
        UIAlertView *alert= [[UIAlertView alloc]initWithTitle:@"Error" message:@"The location services seems to be disabled from the settings." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
        [alert show];
        alert= nil;
    }

    return shouldFetchLocation;
}

Here is my core location delegate method:

- (void)locationManager:(CLLocationManager *)manager
    didUpdateLocations:(NSArray *)locations __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_6_0){

    NSLog(@"location fetched in delegate");

    CLLocation* location = [locations lastObject];
    NSDate* eventDate = location.timestamp;
    NSTimeInterval howRecent = [eventDate timeIntervalSinceNow];

    if (abs(howRecent) < 15.0) {
        // If the event is recent, do something with it.
        NSLog(@"inside loop.... latitude %+.6f, longitude %+.6f\n",
              location.coordinate.latitude,
              location.coordinate.longitude);
    }
    NSLog(@"latitude %+.6f, longitude %+.6f\n",
          location.coordinate.latitude,
          location.coordinate.longitude);
    [self.txtLocation setText:[NSString stringWithFormat:@"\nlatitude: %+.6f \nlongitude:   %+.6f", location.coordinate.latitude, location.coordinate.longitude]];

    [locationManager stopUpdatingLocation];
    [locationManager stopMonitoringSignificantLocationChanges];

    if(locationManager!=nil){
        locationManager.delegate= nil;
        locationManager= nil;
    }
}