iphone - Rotate MapView using Compass orientation

Question

Is it possible to have an embedded MKMapView rotate to always face the direction the iPhone is facing? Basically I want to mimic the Map app rotation feature on my own app.

I see that the iPhone SDK does not expose the functionality. However, I wonder if it would work to rotate the entire view using CGAffineTransformMakeRotate. Would it affect tapping and zooming? Is there a better way?

Answer 1

To rotate the mapView but not the annotations you could use the following code to compensate for the maps rotation.

- (void)locationManager:(CLLocationManager *)manager
       didUpdateHeading:(CLHeading *)newHeading
{
  double rotation = newHeading.magneticHeading * 3.14159 / 180;
  CGPoint anchorPoint = CGPointMake(0, -23); // The anchor point for your pin

  [mapView setTransform:CGAffineTransformMakeRotation(-rotation)];

  [[mapView annotations] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    MKAnnotationView * view = [mapView viewForAnnotation:obj];

    [view setTransform:CGAffineTransformMakeRotation(rotation)];
    [view setCenterOffset:CGPointApplyAffineTransform(anchorPoint, CGAffineTransformMakeRotation(rotation))];

  }];

}

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Another sollution is using a new method that has been added in iOS 5 to MKMapView.

Take a look at: http://developer.apple.com/library/ios/#documentation/MapKit/Reference/MKMapView_Class/MKMapView/MKMapView.html

- (void)setUserTrackingMode:(MKUserTrackingMode)mode animated:(BOOL)animated;