Moving Annotation View on mapkit - objective-c

Question

I have to add annotation view image as a car. I am able to move that car according to the locations I am getting from server. But I am facing problem when I have applied code for rotation of car. Every time, car is turning to new location, it moves and again it goes to its original position(car does not face to front).then again it turns,moves and goes to original position. It should move straight. I want car should face to front and It should turn only when actually there is turning. My code is:
oldLocation.latitude = [[_lat objectAtIndex:i] doubleValue];
oldLocation.longitude = [[_longitude objectAtIndex:i] doubleValue];
newLocation.latitude = [[latNew objectAtIndex:i] doubleValue];
newLocation.longitude = [[longNew objectAtIndex:i] doubleValue];
float getAngle = [self angleFromCoordinate:oldLocation toCoordinate:newLocation];
[UIView animateWithDuration:2 animations:^{
MKAnnotationView *annotationView = (MKAnnotationView *[self.mapView viewForAnnotation:myAnnotation[i]];
annotationView.transform = CGAffineTransformMakeRotation(getAngle);
myAnnotation[i].coordinate = newLocation;
}];
}
- (float)angleFromCoordinate:(CLLocationCoordinate2D)first
toCoordinate:(CLLocationCoordinate2D)second {
float deltaLongitude = second.longitude - first.longitude;
float deltaLatitude = second.latitude - first.latitude;
float angle = (M_PI * .5f) - atan(deltaLatitude / deltaLongitude);
if (deltaLongitude > 0) return angle;
else if (deltaLongitude < 0) return angle + M_PI;
else if (deltaLatitude < 0) return M_PI;
return 0.0f;
}