Question

I have a UITableView in a UINavigationController that contains a rightBarButtonItem which should hide the UITableView and show an MKMapView instead. The button seems to work great: it hides the UITableView, and shows the MKMapView. However, this MKMapView is empty. As in, completely white. I’ve tried to use a UILabel (just for testing purposes), and that doesn’t appear either, so the problem must occur when I add the MKMapView (and UILabel) to the view hierarchy. Some relevant code:

- (void)viewDidLoad {
    [super viewDidLoad];

    self.mapView = [[MKMapView alloc] init];
    mapView.hidden = YES;

    [self.view addSubview:self.mapView];

    // Some other stuff, table set up, etc.
}

That is the viewDidLoad of a class that inherits from UITableViewController. Now, I use the following method that gets called when tapped on the rightBarButtonItem of the UINavigationController:

- (void) toggleView {

    if (self.mapView.isHidden) {

        self.mapView.hidden = NO;
        self.tableView.hidden = YES;
        self.viewButton.title = @"List";
    }

    else {

        self.mapView.hidden = YES;
        self.tableView.hidden = NO;
        self.viewButton.title = @"Map";
    }

}

I am certain that function gets called, I have checked using NSLog. Also, the UITableView correctly disappears, and, I assume, the MKMapView (or whatever other UIView object for that matter) appears, but is empty/completely white. Does anybody see why I’m not seeing maps when trying to switch to Map View?

Answer 1

You should give it a size and position.
CGSize size = self.view.frame.size;
self.mapView =[[MKMapView alloc] initWithFrame:CGRectMake(0,0, size.width, size.height)];

To check the size in the console, add the following line in your toogleview method:
NSLog(@”%@”, self.mapView);