iphone - Rotate image as per the direction of user follows in Map -

i want rotate bike / car image in direction of user follows. right image follows direction looks non directive, can point not follows direction :

- (mkannotationview *)mapview:(mkmapview *)map viewforannotation:(id <mkannotation>)annotation {     static nsstring *annotationviewid = @"annotationviewid";      mkannotationview *annotationview = (mkannotationview *)[map dequeuereusableannotationviewwithidentifier:annotationviewid];      if (annotationview == nil)     {         annotationview = [[[mkannotationview alloc] initwithannotation:annotation reuseidentifier:annotationviewid] autorelease];     }      annotationview.image = [uiimage imagenamed:@"bike.png"];     annotationview.annotation = annotation;      return annotationview; }  - (void)locationmanager:(cllocationmanager *)manager didupdatetolocation:(cllocation *)newlocation fromlocation:(cllocation *)oldlocation {     if (newlocation.horizontalaccuracy < 0)         return;     if  (!newlocation)         return;      currentlocation = newlocation;     if(currentlocation != nil)     {          if (myannotation)         {             [self.mymapview removeannotation:myannotation];         }          cllocationcoordinate2d location = cllocationcoordinate2dmake(currentlocation.coordinate.latitude, currentlocation.coordinate.longitude);         myannotation = [[myannotation alloc] initwithcoordinates:location title:@"current location" subtitle:nil];         [self.mymapview addannotation:myannotation];     } } 

check out core location's -[cllocationmanagerdelegate locationmanager:didupdateheading:].