#pragma mark - 

- (void)drawTestLine
{
    // test code : draw line between Beijing and Hangzhou
    CLLocation *location0 = [[CLLocation alloc] initWithLatitude:39.954245 longitude:116.312455];
    CLLocation *location1 = [[CLLocation alloc] initWithLatitude:30.247871 longitude:120.127683];
    NSArray *array = [NSArray arrayWithObjects:location0, location1, nil];
    [self drawLineWithLocationArray:array];
}

- (void)drawLineWithLocationArray:(NSArray *)locationArray
{
    int pointCount = [locationArray count];
    CLLocationCoordinate2D *coordinateArray = (CLLocationCoordinate2D *)malloc(pointCount * sizeof(CLLocationCoordinate2D));
    
    for (int i = 0; i < pointCount; ++i) {
        CLLocation *location = [locationArray objectAtIndex:i];
        coordinateArray[i] = [location coordinate];
    }
    
    self.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:pointCount];
    [self.mapView setVisibleMapRect:[self.routeLine boundingMapRect]];
    [self.mapView addOverlay:self.routeLine];
    
    free(coordinateArray);
    coordinateArray = NULL;
}

#pragma mark - MKMapViewDelegate
- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id <MKOverlay>)overlay {
    if (overlay == self.routeLine) {
        if (nil == self.lineRender) {
            self.lineRender = [[MKPolylineRenderer alloc] initWithPolyline:self.routeLine];
            self.lineRender.strokeColor = [UIColor redColor];
            self.lineRender.lineWidth = 5.f;
        }
        
        return self.lineRender;
    }
    
    return nil;
}