Question

I’m creating a Map app in iPhone using MKMapView.

I did successfully find my current location and zoom on that point like this:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.mapView.delegate = self;

    self.locationManager = [[CLLocationManager alloc] init];
    [locationManager setDelegate:self];

    [locationManager setDistanceFilter:kCLDistanceFilterNone];
    [locationManager setDesiredAccuracy:kCLLocationAccuracyBest];

    [self.mapView setShowsUserLocation:YES];
}

-(void) mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views
{
    MKAnnotationView *annotationView = [views objectAtIndex:0];
    id<MKAnnotation> mp = [annotationView annotation];

    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance([mp coordinate], 1550, 1550);
    [self.mapView setRegion:region animated:YES];
}

The problem that I want to solve is:

I have a location on the map (this code in viewDidLoad):

CLLocationCoordinate2D location = [self getLocationFromAddressString:@"San Francisco, CA, United States"];
//    location.latitude = 37.78608;
//    location.longitude = -122.407398;

    MapViewAnnotation *mapAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"Store location" coordinate:location];
    [self.mapView addAnnotation:mapAnnotation];

and this is the mapViewAnnotation:

@implementation MapViewAnnotation

@synthesize title = _title;
@synthesize coordinate = _coordinate;

- (id) initWithTitle:(NSString *) t coordinate:(CLLocationCoordinate2D) c {
    self = [super init];
    if(self) {
        _title = t;
        _coordinate = c;
    }
    return self;
}
@end

I want to have a proper zoomLevel and mapCenter for this location and my current location.

I could do that successfully in Android using MapController.zoomToSpan(). How can I fix it in iPhone Map?

Answer 1

This is the way that I could implement it:

    CLLocationCoordinate2D topLeftCoord;
    topLeftCoord.latitude = -90;
    topLeftCoord.longitude = 180;

    CLLocationCoordinate2D bottomRightCoord;
    bottomRightCoord.latitude = 90;
    bottomRightCoord.longitude = -180;

    for(id<MKAnnotation> annotation in mapView.annotations) {
        topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
        topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);
        bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
        bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
    }

    MKCoordinateRegion region;
    region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5;
    region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;
    region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1;

    // Add a little extra space on the sides
    region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1;

    region = [mapView regionThatFits:region];
    [mapView setRegion:region animated:YES];