How to pass map data to be displayed by another class?

Question

I’m using Google’s Maps API for iOS. I was doing some testing and I set up a UIView as a subclass of GMSMapView and kept a pointer for her in ViewController, getting:

#import <UIKit/UIKit.h>
#import <GoogleMaps/GoogleMaps.h>
#import <CoreLocation/CoreLocation.h>
@interface ViewController : UIViewController<GMSMapViewDelegate, CLLocationManagerDelegate>
{
    CLLocationManager *locationManager;
}
@property (strong, nonatomic) IBOutlet GMSMapView *meuMapa;

@end

And I did its implementation in another class, this way:

-(GMSMapView*)criaMapa{
 // Create a GMSCameraPosition that tells the map to display the
    // coordinate -33.86,151.20 at zoom level 6.
    GMSCameraPosition *camera = [GMSCameraPosition
                                 cameraWithLatitude:-22.530351
                                 longitude:-43.071199
                                 zoom:17];
    _mapaCriado = [GMSMapView mapWithFrame:CGRectZero camera:camera];

    #pragma mark - Coloca Pinos no Mapa

    // Uma posição em Niteroi
    GMSMarker *marker = [[GMSMarker alloc] init];
    marker.position = CLLocationCoordinate2DMake(-22.530303,-43.071033);
    marker.title = @"Ponto B";
    marker.snippet = @"Detalhes";

    marker.map = _mapaCriado;

    return _mapaCriado;
}

Getting back in ViewController.m in the method -(void)viewDidLoad i get the map that was created in another class:

- (void)viewDidLoad {
    CriaMapas mapFact = [[CriaMapas alloc]init];
    self.meuMapa = [mapFact criaMapa];
}

But the map is started with nothing, as if there had been no initialization and no creation of Marker.

How could you do this: Create the map in another class and return it to be displayed?

Answer 1

Turns out you can’t just assign to meuMapa another GMSMapView, besides this first being a IBOutlet.

As the creation of your map is done dynamically, you also need to add the map to your own view in the same way. So, this IBOutlet can be replaced by a Base View that will receive the map:

@property (strong, nonatomic) IBOutlet UIView *mapaContainer;

And then create to add the map as subview of this above:

- (void)viewDidLoad {
    CGRect rect = [mapaContainer frame];
    CriaMapas mapFact = [[CriaMapas alloc] init];

    GMSMapView meuMapa = [mapFact criaMapa];
    [meuMapa setFrame:CGRectMake(0.0f, 0.0f, [rect.size width], [rect.size height])];

    [self.mapaContainer addSubview:meuMapa];
}

You can also change your method criaMapa to be able to directly receive the map dimensions, so you do not need to define the frame outside.