Use of undeclared identifier 'locationManager' - objective-c

Question

I'm trying to follow this tutorial:
http://www.appcoda.com/how-to-get-current-location-iphone-user/
Everything is fine till I add this line:
locationManager = [[CLLocationManager alloc] init];
Then I get the error.
I also get errors for these lines: (Xcode suggests I use "_LongitudeLabel"?
if (currentLocation != nil) {
longitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.longitude];
latitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.latitude];
}
Any idea what's wrong? Does the tutorial have errors or have I done something wrong?
Thanks!
This is ViewController.m file:
#import "ViewController.h"
#implementation MyLocationViewController {
CLLocationManager *locationManager;
}
#end
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
locationManager = [[CLLocationManager alloc] init];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)getCurrentLocation:(id)sender {
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
}
#pragma mark - CLLocationManagerDelegate
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
NSLog(#"didFailWithError: %#", error);
UIAlertView *errorAlert = [[UIAlertView alloc]
initWithTitle:#"Error" message:#"Failed to Get Your Location" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[errorAlert show];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSLog(#"didUpdateToLocation: %#", newLocation);
CLLocation *currentLocation = newLocation;
if (currentLocation != nil) {
longitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.longitude];
latitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.latitude];
}
}
#end
This is ViewController.h file:
// ViewController.h
// MyLocationDemo
//
// Created by Ian Nicoll on 12/11/14.
// Copyright (c) 2014 Ian Nicoll. All rights reserved.
//
#import <CoreLocation/CoreLocation.h>
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *LatitudeLabel;
#property (weak, nonatomic) IBOutlet UILabel *LongitudeLabel;
#property (weak, nonatomic) IBOutlet UILabel *addressLabel;
- (IBAction)getCurrentLocation:(id)sender;
#end
#interface MyLocationViewController : UIViewController <CLLocationManagerDelegate>
#end

Answer 1

The first issue is an error on your part. You declared locationManager in MyLocationViewController but try to initialize it in the viewDidLoad of ViewController, where it of course does not exist.
The second issue is an issue with the instructions. When you declare an #property, the default behavior is to create an instance variable with an underscore in front of it.
So #property (weak, nonatomic) IBOutlet UILabel *LatitudeLabel; can be accessed as self.latitudeLabel (which goes through the setter/getter) or just _latitudeLabel which accesses the ivar directly. The latter is probably what you want.

Answer 2

Ok so the build now is Succeeded (though I'm not 100& sure I got things right) but now I get a warning for this line: locationManager.delegate = self; - Assigning to 'id'from incompatible type 'ViewControler *const_strong'
Would you know how to fix this warning?
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController {
CLLocationManager *locationManager;
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
locationManager = [[CLLocationManager alloc] init];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)getCurrentLocation:(id)sender {
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
}
#pragma mark - CLLocationManagerDelegate
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
NSLog(#"didFailWithError: %#", error);
UIAlertView *errorAlert = [[UIAlertView alloc]
initWithTitle:#"Error" message:#"Failed to Get Your Location" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[errorAlert show];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSLog(#"didUpdateToLocation: %#", newLocation);
CLLocation *currentLocation = newLocation;
if (currentLocation != nil) {
_LongitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.longitude];
_LatitudeLabel.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.latitude];
}
}
#end