How to setRegion with google maps sdk for iOS?

问题:

How to setRegion with google maps sdk for iOS? I want set zoom for location and radius of markers.

回答1:

UPDATE:

The original answer below is obsolete as of version 1.2 of the SDK - you can now use the fitBounds: method of the GMSCameraUpdate class:

https://developers.google.com/maps/documentation/ios/reference/interface_g_m_s_camera_update

---

Original answer:

The MKMapPoint type in MapKit defines a 2D projection of a map. Although the actual values of the projection are meant to be opaque, they turn out to be equivalent to pixels at zoom level 20. This can be used to convert lat/lon values to pixels, and therefore a scale, and therefore a zoom level.

Start by defining two locations which specify the bounds of the region you want to display. These could be opposite corners of the bounding box, or just two locations, for example:

CLLocationCoordinate2D location1 = 
    CLLocationCoordinate2DMake(-33.8683, 151.2086); // Sydney
CLLocationCoordinate2D location2 = 
    CLLocationCoordinate2DMake(-31.9554, 115.8585); // Perth

If you have more than two points that you want to include, you could calculate the bounds of them yourself. This can also be done using GMSCoordinateBounds, for example:

GMSCoordinateBounds* bounds =
    [[GMSCoordinateBounds alloc]
    initWithCoordinate: CLLocationCoordinate2DMake(-33.8683, 151.2086) // Sydney
    andCoordinate: CLLocationCoordinate2DMake(-31.9554, 115.8585)]; // Perth
bounds = [bounds including: 
    CLLocationCoordinate2DMake(-12.4667, 130.8333)]; // Darwin
CLLocationCoordinate2D location1 = bounds.southWest;
CLLocationCoordinate2D location2 = bounds.northEast;

Next, you need to get the size of the map view in points. You could use this:

float mapViewWidth = _mapView.frame.size.width;
float mapViewHeight = _mapView.frame.size.height;

But that will only work if you've already created the map view. Also, if you're using the sample code in the getting started guide, the frame is set to CGRectZero, as the actual size will be set later to fill the screen. In these cases if you're creating a full-screen map then you might want something like this:

float mapViewWidth = [UIScreen mainScreen].applicationFrame.size.width;
float mapViewHeight = [UIScreen mainScreen].applicationFrame.size.height;

Otherwise, use the size which you're creating your map view with.

Now you have the info necessary to calculate the camera position:

MKMapPoint point1 = MKMapPointForCoordinate(location1);
MKMapPoint point2 = MKMapPointForCoordinate(location2);

MKMapPoint centrePoint = MKMapPointMake(
    (point1.x + point2.x) / 2,
    (point1.y + point2.y) / 2);
CLLocationCoordinate2D centreLocation = MKCoordinateForMapPoint(centrePoint);

double mapScaleWidth = mapViewWidth / fabs(point2.x - point1.x);
double mapScaleHeight = mapViewHeight / fabs(point2.y - point1.y);
double mapScale = MIN(mapScaleWidth, mapScaleHeight);

double zoomLevel = 20 + log2(mapScale);

GMSCameraPosition *camera = [GMSCameraPosition
    cameraWithLatitude: centreLocation.latitude
    longitude: centreLocation.longitude
    zoom: zoomLevel];

You can then initialize the map view with this camera, or set the map view to this camera.

For this code to compile, you will need to add the MapKit framework to your project, and then also import it:

#import <MapKit/MapKit.h>

Note that this code doesn't handle wrap-around if your coordinates span across the date line. For example if you tried using this code with Tokyo and Hawaii, instead of displaying an area of the Pacific, it will try to display almost the entire world. In portrait mode it's not possible to zoom out far enough to see Hawaii on the left and Tokyo on the right, and so the map ends up centred on Africa with neither location visible. You could modify the above code to handle the wrap-around at the date line if you wanted to.

回答2:

UPDATE

All issues were fixed in the latest version of Google maps (1.5). Standard method [mapView_ animateWithCameraUpdate:[GMSCameraUpdate fitBounds:bounds]]; can noow be used instead of the code below

---

ORIGINAL ANSWER

[GMSCameraUpdate fitBounds] does not give accurate results in my version of the SDK (1.2.0). I am using the code below instead of it. The formulae are taken from the Mercator Projection. The world is latitudonally bounded at 85 degrees as per Google Documentation.

#import <stdlib.h>

-(void) animateBoundsNorth:(CGFloat)north West:(CGFloat)west South:(CGFloat)south East:(CGFloat)east Padding:(int)padding {

    CGFloat northRad = north * M_PI / 180.0;
    CGFloat northProj = logf(tanf(M_PI_4 + northRad/2.0));
    CGFloat southRad = south * M_PI / 180.0;
    CGFloat southProj = logf(tanf(M_PI_4 + southRad/2.0));
    CGFloat topRad = 85.0 * M_PI / 180.0;
    CGFloat topProj = logf(tanf(M_PI_4 + topRad/2.0));
    CGFloat zoomLat = log2f((mapView_.bounds.size.height - padding * 2) * 2 * topProj /(northProj - southProj)) - 8;
    CGFloat zoomLon = log2f((mapView_.bounds.size.width - padding * 2) * 360/(east - west)) - 8;

    GMSCameraUpdate *update = [GMSCameraUpdate setTarget:CLLocationCoordinate2DMake((north+south)/2.0, (west+east)/2.0) zoom:MIN(zoomLat, zoomLon)];


    [mapView_ animateWithCameraUpdate:update];


}

回答3:

Saxun Druce's answer is really good. But in addition, if you want to calculate a radius from any location you can do that with the following code:

    CLLocationCoordinate2D center = CLLocationCoordinate2DMake([currentLocationLat doubleValue],[currentLocationLong doubleValue]);
float radius = 25*1000; //radius in meters (25km)

MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(center, radius*2, radius*2);

CLLocationCoordinate2D  northEast = CLLocationCoordinate2DMake(region.center.latitude - region.span.latitudeDelta/2, region.center.longitude - region.span.longitudeDelta/2);
CLLocationCoordinate2D  southWest = CLLocationCoordinate2DMake(region.center.latitude + region.span.latitudeDelta/2, region.center.longitude + region.span.longitudeDelta/2);

GMSCoordinateBounds* bounds = [[GMSCoordinateBounds alloc]
                               initWithCoordinate: northEast
                               andCoordinate: southWest];

回答4:

If you have latitude and longitude of 'far-left' and 'near-right' corners of the google map ,you can display the data in swift using below code

     var region:GMSVisibleRegion = GMSVisibleRegion()
     region.nearLeft = CLLocationCoordinate2DMake(nearleflat, nearleftlong)
     region.farRight = CLLocationCoordinate2DMake(fareastlat,fareastlong)
     let bounds = GMSCoordinateBounds(coordinate: region.nearLeft,coordinate: region.farRight)
     let camera = googleMapView.cameraForBounds(bounds, insets:UIEdgeInsetsZero)
     googleMapView.camera = camera;

This link may also be helpful for related things.

回答5:

I currently using this method.

self.markers is a dictionary with markers stored by a location ID, self.currentLocation is a CLLocation2D, and self.mapView is a GMSMapView.

The maths here is a check on whether to match the sizes on the width or the height, and then a calculation of the zoom based on the fact that x1 / pow(2, zoom1) = x2 / pow(2, zoom2)", leading to zoom2 = log2(x2 * pow(2, self.mapView.camera.zoom) / x1).

- (void)fitMarkers
{
    if (2 > self.markers.count)
    {
        [self.mapView animateToCameraPosition:[GMSCameraPosition cameraWithTarget:self.currentLocation.coordinate zoom:kZoom]];

        return;
    }

    NSArray* markers = self.markers.allValues;

    GMSCoordinateBounds* markerBounds = [[GMSCoordinateBounds alloc] initWithCoordinate:((id<GMSMarker>)markers[0]).position andCoordinate:((id<GMSMarker>)markers[1]).position];

    for (id<GMSMarker> marker in markers)
    {
        markerBounds = [markerBounds including:marker.position];
    }

    // get marker bounds in points
    CGPoint markerBoundsTopLeft = [self.mapView.projection pointForCoordinate:CLLocationCoordinate2DMake(markerBounds.northEast.latitude, markerBounds.southWest.longitude)];
    CGPoint markerBoundsBottomRight = [self.mapView.projection pointForCoordinate:CLLocationCoordinate2DMake(markerBounds.southWest.latitude, markerBounds.northEast.longitude)];

    // get user location in points
    CGPoint currentLocation = [self.mapView.projection pointForCoordinate:self.currentLocation.coordinate];

    CGPoint markerBoundsCurrentLocationMaxDelta = CGPointMake(MAX(fabs(currentLocation.x - markerBoundsTopLeft.x), fabs(currentLocation.x - markerBoundsBottomRight.x)), MAX(fabs(currentLocation.y - markerBoundsTopLeft.y), fabs(currentLocation.y - markerBoundsBottomRight.y)));

    // the marker bounds centered on self.currentLocation
    CGSize centeredMarkerBoundsSize = CGSizeMake(2.0 * markerBoundsCurrentLocationMaxDelta.x, 2.0 * markerBoundsCurrentLocationMaxDelta.y);

    // inset the view bounds to fit markers
    CGSize insetViewBoundsSize = CGSizeMake(self.mapView.bounds.size.width - kMarkerSize / 2.0 - kMarkerMargin, self.mapView.bounds.size.height - kMarkerSize / 2.0 - kMarkerSize);

    CGFloat x1;
    CGFloat x2;

    // decide which axis to calculate the zoom level with by comparing the width/height ratios
    if (centeredMarkerBoundsSize.width / centeredMarkerBoundsSize.height > insetViewBoundsSize.width / insetViewBoundsSize.height)
    {
        x1 = centeredMarkerBoundsSize.width;
        x2 = insetViewBoundsSize.width;
    }
    else
    {
        x1 = centeredMarkerBoundsSize.height;
        x2 = insetViewBoundsSize.height;
    }

    CGFloat zoom = log2(x2 * pow(2, self.mapView.camera.zoom) / x1);

    GMSCameraPosition* camera = [GMSCameraPosition cameraWithTarget:self.currentLocation.coordinate zoom:zoom];

    [self.mapView animateToCameraPosition:camera];
}

回答6:

As per new release of GoogleMaps iOS sdk 1.9.2, We can set up using Camera's position, zoom level, viewingAngle.

GMSCameraPosition* camera = [GMSCameraPosition cameraWithLatitude:28.6100
                                                            longitude:77.2300
                                                                 zoom:14.0
                                                              bearing:0
                                                         viewingAngle:0.00];
    self.mapView = [GMSMapView mapWithFrame:CGRectMake(0, 45, self.view.frame.size.width, self.view.frame.size.height - 45) camera:camera];
    mapView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    mapView.delegate = self;
    mapView.myLocationEnabled = YES;
    mapView.mapType = kGMSTypeTerrain;
    mapView.settings.compassButton = YES;
    mapView.settings.myLocationButton = YES;
    [self.mapView setMinZoom:10 maxZoom:18];

    GMSMarker* marker = [[GMSMarker alloc] init];
    marker.position = CLLocationCoordinate2DMake(28.6100, 77.2300);
    marker.title = @"New Delhi";
    marker.snippet = @"Capital Of India";

    marker.map = self.mapView;
    marker.appearAnimation = kGMSMarkerAnimationPop;
    marker.icon = [GMSMarker markerImageWithColor:[UIColor grayColor]];
    [self.view addSubview:self.mapView];

For Further reference see this PDF document.

you can also set minimum and maximum Zoom level as per your need:

[self.mapView setMinZoom:10 maxZoom:30];

Hope this solves the problem.

回答7:

I searched through the header files of the framework and only found the interface that could be used for the following code which could be a start. The problem here is that i can not find any imports of GMSCoordinateBounds in one of the other headers so i can not find a way to display this region in GMSMapView.

GMSVisibleRegion region;
region.farLeft = CLLocationCoordinate2DMake(farLeftLatitude, farLeftlongitude);
region.farRight = CLLocationCoordinate2DMake(farRightlatitude, farRightlongitude); 

GMSCoordinateBounds *bounds = [[GMSCoordinateBounds alloc] initWithRegion:region];

回答8:

As of June 2014, this answer is the simplest way to iterate over a given array of markers and then set bounds accordingly.

回答9:

// I have found this method that worked for me

func setMapZoomToRadius(lat:Double, lng:Double, var mile:Double)
    {

        let center = CLLocationCoordinate2DMake(lat, lng)           
        let radius: Double = (mile ) * 621.371 

        let region = MKCoordinateRegionMakeWithDistance(center, radius * 2.0, radius * 2.0)


        let northEast = CLLocationCoordinate2DMake(region.center.latitude - region.span.latitudeDelta, region.center.longitude - region.span.longitudeDelta)
        let  southWest = CLLocationCoordinate2DMake(region.center.latitude + region.span.latitudeDelta, region.center.longitude + region.span.longitudeDelta)


        print("\(region.center.longitude)  \(region.span.longitudeDelta)")
        let bounds = GMSCoordinateBounds(coordinate: southWest, coordinate: northEast)

        let camera = googleMapView.cameraForBounds(bounds, insets:UIEdgeInsetsZero)
         googleMapView.camera = camera;

      }