地图画线，实现轨迹回放

    //将经，纬度加入数组
   CLLocation *nowLocation = [[CLLocation alloc] initWithLatitude:coords.latitude longitude:coords.longitude];
    [rePlayArray addObject:nowLocation];



//直接调用就画线了
 [ self drawLineWithLocationArray:rePlayArray]; //rePlayArray加载的所有CLLocation



- ( void )drawLineWithLocationArray:( NSArray *)locationArray
{
    // create a c array of points.
    MKMapPoint* pointArray = malloc( sizeof (CLLocationCoordinate2D) * locationArray.count);

    // for(int idx = 0; idx < pointStrings.count; idx++)
    for ( int idx = 0; idx < locationArray.count; idx++)
    {
        CLLocation *location = [locationArray objectAtIndex:idx];
        CLLocationDegrees latitude  = location.coordinate.latitude;
        CLLocationDegrees longitude = location.coordinate.longitude;

        // create our coordinate and add it to the correct spot in the array
        CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(latitude, longitude);
        MKMapPoint point = MKMapPointForCoordinate(coordinate);
        pointArray[idx] = point;
    }

    if (routeLine) {
        [_mapView removeOverlay:routeLine];
    }

    routeLine = [MKPolyline polylineWithPoints:pointArray count:locationArray.count];

    // add the overlay to the map
    if ( nil != routeLine) {
        [_mapView addOverlay:routeLine];
    }

    // clear the memory allocated earlier for the points
    free(pointArray);
}




- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:( id <MKOverlay>)overlay {
    MKOverlayView* overlayView = nil ;

    if (overlay == routeLine)
    {
        //if we have not yet created an overlay view for this overlay, create it now.
        routeLineView = [[MKPolylineView alloc] initWithPolyline:routeLine];

        if (current_type == _CURRENT_TRACK)
        {
            routeLineView.fillColor = [UIColor blueColor];
            routeLineView.strokeColor = [UIColor blueColor];
        } else
        {
            routeLineView.fillColor = [UIColor redColor];
            routeLineView.strokeColor = [UIColor redColor];
        }
        routeLineView.lineWidth = 6;
        overlayView = routeLineView;
        return overlayView;
    }     return nil ;
}