Question

I’m trying to get an MKMapView show my current location. I managed to get this working in an application with a single view, but now I’m trying to implement the same view inside a UITabBarController. My code is more or less the same, but I still can’t get it to work.

I’m following the BigNerdRanch guide on iPhone development. I implemented the view like they did with the other views in the book; I first wrote the init method:

#import "CurrentLocationViewController.h"
#import "MapPoint.h"

@implementation CurrentLocationViewController

    - (id)init
    {
        self = [super initWithNibName:@"CurrentLocationViewController"
                               bundle:nil];
        if (self) {
            UITabBarItem *tbi = [self tabBarItem];
            [tbi setTitle:@"Location"];

            UIImage *i = [UIImage imageNamed:@"Hypno.png"];
            [tbi setImage:i];

            locationManager = [[CLLocationManager alloc] init];
            [locationManager setDelegate:self];
            [locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
            [locationManager setDistanceFilter:kCLDistanceFilterNone];

            [worldView setShowsUserLocation:YES];

        }

        return self;
    }

And I made that init method the designated initializer by doing this aswell:

-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    return [self init];
}

As you can see, I did call setShowsUserLocation:YES on my worldview which is declared as: IBOutlet MKMapView *worldView; in my header file.

I’m probably missing something here, but I thought that message was the only thing I needed to get the basic mapview working? Any ideas?

I can provide more code if necessary. The view does load properly btw, I checked with an obnoxious colour first and it does show the map. It just doesn’t put a blue pin on it.

Thanks.

Answer 1

You’ve created the MapView in a xib file, have you made sure that you have connected the worldView outlet?

Also, you don’t need to set up CoreLocation for this. Just for comparison – here’s my controller definition for the same exercise. It doesn’t show – but I set the shows user location property in the xib file rather than in code.

#import "MapViewController.h"

@implementation MapViewController
@synthesize mapView;

// New designated initialiser
-(id)init {
    if (!(self = [super initWithNibName:@"MapViewController" bundle:nil])) {
        return nil; // Bail!
    }
    UITabBarItem *tbi = self.tabBarItem;
    tbi.title = @"Map";
    tbi.image = nil;

    return self;
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    return [self init];
}

- (void)dealloc {
    [mapView release];
    [super dealloc];
}

#pragma mark - View lifecycle

- (void)viewDidUnload {
    [self setMapView:nil];
    [super viewDidUnload];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - MapKit delegate methods

- (void)mapView:(MKMapView *)aMapView didUpdateUserLocation:(MKUserLocation *)userLocation {
    CLLocationCoordinate2D loc = [userLocation.location coordinate];
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(loc, 1000.0f, 1000.0f);
    [aMapView setRegion:region animated:YES];
}

@end