OpenStreetMap code

#import "ViewController.h"

@import MapKit;

@interface ViewController () <MKMapViewDelegate>
@property (strong, nonatomic) IBOutlet MKMapView *mapView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.mapView.delegate = self;

    NSString *template = @"http://tile.openstreetmap.org/{z}/{x}/{y}.png";
    MKTileOverlay *overlay = [[MKTileOverlay alloc] initWithURLTemplate:template];
    overlay.canReplaceMapContent = YES;
    [self.mapView addOverlay:overlay level:MKOverlayLevelAboveLabels];
}

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay {
    if ([overlay isKindOfClass:[MKTileOverlay class]]) {
        return [[MKTileOverlayRenderer alloc] initWithTileOverlay:overlay];
    }
    return nil;
}

@end