Core location wont work - ios

Question

I have been trying to make an app that allows the user to retrieve the current location using the core location framework. I wanted to be able to get the coordinates of the device that is using the app when the app launches and be able to display them using UILabels. Can someone please tell me what i am doing wrong or what adjustments I should make to the code?
Header file:
#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
#interface ViewController : UIViewController
#property (strong, nonatomic) IBOutlet UILabel *longitude;
#property (strong, nonatomic) IBOutlet UILabel *latitude;
#property (strong, nonatomic) IBOutlet UILabel *altitude;
#property (strong, nonatomic) IBOutlet UILabel *speed;
#end
Implementation file:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
CLLocationManager *locationManager;
[super viewDidLoad];
locationManager = [[CLLocationManager alloc]init]; // initializing locationManager
locationManager.delegate = self; // I set the delegate of locationManager to self.
locationManager.desiredAccuracy = kCLLocationAccuracyBest; // setting the accuracy
[locationManager startUpdatingLocation]; //requesting location updates
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error{
UIAlertView *errorAlert = [[UIAlertView alloc]initWithTitle:#"Error" message:#"There was an error retrieving your location" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles: nil];
[errorAlert show];
NSLog(#"Error: %#",error.description);
}
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *crnLoc = [locations lastObject];
_latitude.text = [NSString stringWithFormat:#"%.8f",crnLoc.coordinate.latitude];
_longitude.text = [NSString stringWithFormat:#"%.8f",crnLoc.coordinate.longitude];
_altitude.text = [NSString stringWithFormat:#"%.0f m",crnLoc.altitude];
_speed.text = [NSString stringWithFormat:#"%.1f m/s", crnLoc.speed];
}
#end
I get these 2 errors.
Assigning to 'id<CLLocationManagerDelegate> _Nullable' from incompatible type 'ViewController *const __strong'
'UIAlertView' is deprecated: first deprecated in iOS 9.0 - UIAlertView is deprecated. Use UIAlertController with a preferredStyle of UIAlertControllerStyleAlert instead

Answer 1

You're not implementing the CLLocationManagerDelegate protocol, which is why you get the first error. You could implement it like this:
#interface ViewController () <CLLocationManagerDelegate>
#end
You should also check the documentation for the methods that you'll need to implement in order to conform to that protocol, which you'll have to write in your #implementation. Only after conforming to that protocol is this assignment allowed:
locationManager.delegate = self; // I set the delegate of locationManager to self.
The second issue appears to be a warning. Apple did deprecate UIAlertView in iOS 9.0 and it has been replaced by UIAlertController, so you should use that instead. This NSHipster article explains how to use and compares it with the old, deprecated, version, which is interesting, but it's in Swift (I'm leaving it for the discussion they present). Here you'll also find some examples in Objective-C. Here's an example as shown on that last link:
UIAlertController * view= [UIAlertController
alertControllerWithTitle:#"My Title"
message:#"Select you Choice"
preferredStyle:UIAlertControllerStyleActionSheet];
UIAlertAction* ok = [UIAlertAction
actionWithTitle:#"OK"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
//Do some thing here
[view dismissViewControllerAnimated:YES
completion:nil];
}];
UIAlertAction* cancel = [UIAlertAction
actionWithTitle:#"Cancel"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
[view dismissViewControllerAnimated:YES completion:nil];
}];
[view addAction:ok];
[view addAction:cancel];
[self presentViewController:view animated:YES completion:nil];