iOS Location permission not work to show by Objective-C - ios

Question

I create a sample project to get user location.
But When I run the app, the location permission not show to me.
What's wrong with my code?
Thanks.
ViewController.h
#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
#interface ViewController : UIViewController<CLLocationManagerDelegate>
#property (nonatomic, strong) CLLocationManager *locationManager;
#end
ViewController.m
#import "ViewController.h"
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UILabel *latLabel;
#property (weak, nonatomic) IBOutlet UILabel *longLabel;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.locationManager.delegate = self;
[self.locationManager requestWhenInUseAuthorization];
[self.locationManager startUpdatingLocation];
}
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations{
CLLocation *currentLocation = [locations lastObject];
if(currentLocation != nil){
self.latLabel.text = [NSString stringWithFormat:#"%.2f",currentLocation.coordinate.latitude];
self.longLabel.text = [NSString stringWithFormat:#"%.2f",currentLocation.coordinate.longitude];
[self.locationManager stopUpdatingLocation];
}
}
#end

Answer 1

You need to start by checking locationServicesEnabled. If they are enabled, preceed to call authorizationStatus to learn your app's actual authorization status. You ask for the authorization dialog only if the status is "not determined".
If the status is anything else, there is no point asking for the authorization dialog; it won't appear.
Another problem is that this code is useless:
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations{
CLLocation *currentLocation = [locations lastObject];
if(currentLocation != nil){
self.latLabel.text = [NSString stringWithFormat:#"%.2f",currentLocation.coordinate.latitude];
self.longLabel.text = [NSString stringWithFormat:#"%.2f",currentLocation.coordinate.longitude];
[self.locationManager stopUpdatingLocation];
}
}
You are calling stopUpdatingLocation as soon as you get your first location update. But the chances of your getting a useful location on the first location update are basically nil, because the sensors are just warming up.
(Also please note that it is pointless to check "Location updates" in your background modes. You will not get any location updates in the background unless you set the location manager's allowsBackgroundLocationUpdates to YES, and you are not doing that.)