Rotate GMSMarker in direction at which user facing

问题

I have requirement like on my current location one view will display. It will rotate if device was rotate or location will be change.I research lot but got all the code which have a fix location or angle at some location but i haven't fix location. Can anyone drive me at right direction.

I also used rotation property of the GMSMarker but it is not working.

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
{
    if (newHeading.headingAccuracy < 0){
        NSLog(@"heading accuracy < 0");
        return;
    }

    // Convert Degree to Radian and move the needle
    float oldRad =  (- manager.heading.trueHeading) * M_PI / 180.0f;
    float newRad =  (- newHeading.trueHeading) * M_PI / 180.0f;

    // Compass animation
    CABasicAnimation *theAnimation;
    theAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    theAnimation.fromValue = [NSNumber numberWithFloat:oldRad];
    theAnimation.toValue   = [NSNumber numberWithFloat:newRad];
    theAnimation.duration  = 0.5f;
    [source.layer addAnimation:theAnimation forKey:@"animateMyRotation"];

//    source.transform =  CGAffineTransformMakeRotation(newRad)
//    GMSMarker *source = [googleMap selectedMarker];
//    source.rotation = newRad;
}

Update: I have rotation method but is there any way to rotate the GMSMarker because there is no method for transform.

How uber rotate their car in google map?

回答1:

Current location 'CLLocation' object has a property called 'course'

@property(readonly, nonatomic) CLLocationDirection course;

of type CLLocationDirection(typedef of double) which is an angle of the location.

For car to rotate, You need extra field in your backend, direction, along with latitude and longitude. Use this information to rotate car by applying Transform on UIView

CGAffineTransformMakeRotation(M_PI * (course_of_location) / 180.0);

回答2:

We can rotate image based on course property CLLocation Class

    let marker:GMSMarker = GMSMarker.init(position: currentLocation!)
    let head = locationManager.location?.course ?? 0
    marker.rotation = head
    marker.icon = UIImage(named: "testyCar.png")
    marker.map = mapView

回答3:

you can do something like -

-(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {

    CLLocationDirection direction = newHeading.trueHeading;
    lastDriverAngleFromNorth = direction;
    self.driverMarker.rotation = lastDriverAngleFromNorth - mapBearing;
}

#pragma mark - GMSMapViewDelegate

- (void)mapView:(GMSMapView *)mapView didChangeCameraPosition:(GMSCameraPosition *)position {

    mapBearing = position.bearing;
    self.driverMarker.rotation = lastDriverAngleFromNorth - mapBearing;
}

回答4:

//just do this only

- (void)locationManager:(CLLocationManager *)manager  didUpdateHeading:(CLHeading *)newHeading
{
   double heading = newHeading.trueHeading;
   marker.groundAnchor = CGPointMake(0.5, 0.5);
   marker.rotation = heading;
   marker.map = mapView;
}

回答5:

Try this, it worked for me

func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading:CLHeading) {
    UIView.animate(withDuration: 0.005) {
       let angle = newHeading.trueHeading.toRadians() // convert from degrees to radians
       self.yourImageHere.transform = CGAffineTransform(rotationAngle: CGFloat(angle)) // rotate the picture
    }
}
override func viewDidLoad() {
   super.viewDidLoad()
   locationManager.startUpdatingHeading()
}

回答6:

marker.rotation = course_of_location;

Note: rotation to pin will happen only during movement. in case of static device there will be -1 value of location.course. Also this have no relation with device orientation. If you are looking to move pin according to device heading then do this

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {
marker.rotation =  (manager.heading.trueHeading) * M_PI / 180.0f; }

回答7:

Here the code modified with the changes suggested by Oren Trutner and from me:

You just need to pass old location and new location. By passing required data you will get rotation value which is in float.

#define degreesToRadians(x) (M_PI * x / 180.0)
#define radiansToDegrees(x) (x * 180.0 / M_PI)

- (float)getHeadingForDirectionFromCoordinate:(CLLocationCoordinate2D)fromLoc toCoordinate:(CLLocationCoordinate2D)toLoc
{
    float fLat = degreesToRadians(fromLoc.latitude);
    float fLng = degreesToRadians(fromLoc.longitude);
    float tLat = degreesToRadians(toLoc.latitude);
    float tLng = degreesToRadians(toLoc.longitude);

    float degree = radiansToDegrees(atan2(sin(tLng-fLng)*cos(tLat), cos(fLat)*sin(tLat)-sin(fLat)*cos(tLat)*cos(tLng-fLng)));

    if (degree >= 0) {
        return degree;
    } else {
        return 360+degree;
    }
}

回答8:

Swift 4+

Thanks to priya.vr. When you updating location marker, try this:

 let locationManager = CLLocationManager()
 marker.position = position
 marker.appearAnimation = .none
 marker.rotation = locationManager.location?.course ?? 0
 marker.map = map

来源：https://stackoverflow.com/questions/36450526/rotate-gmsmarker-in-direction-at-which-user-facing

标签

ios

objective-c

google-maps-markers

cllocationmanager

gmsmapview