iPhone MKMapView上显示蓝色污迹

Question

偶尔，我的MKMapView会显示蓝色污迹。 似乎与我手动重新调整大小和在地图上移动有关。 Iphone6 +和iPhone7 + Xcode 8

绘制蓝色路线的代码.....................

添加路线覆盖：

            // Draw route line (Add data for map route from prev location to latest, if prev):
                CLLocationCoordinate2D coordinateArray[2];
                coordinateArray[0] = GPS_location_file[ previous_record ];      // prev GPS
                coordinateArray[1] = GPS_location_file[ new_record_index ];         // this latest GPS

                //  Sets MKPolyline routeLine to these 2 latest route points:
                view_controller.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:2];

                //[view_controller.mapView.visibleMapRect:[view_controller.routeLine boundingMapRect]]; //If you want the route to be visible

                // Adds new overlay with latest two route lines to map:
                [view_controller.mapView addOverlay: view_controller.routeLine];

代表请求在MKMAPVIEW上显示路线：

• （MKOverlayRenderer *）mapView：（MKMapView *）mapView rendererForOverlay：（id）overlay { printf（＆＃34; \ n％s：＆＃34;， FUNCTION ）; // if（overlay == self.routeLine） // { // printf（＆＃34; \ n self.routeLine＆＃34;）; // if（nil == self.routeLineView） // { // printf（＆＃34; \ n nil == self.routeLineView＆＃34;）;

      MKPolylineRenderer *renderer = [[MKPolylineRenderer alloc] initWithOverlay:overlay];
      renderer.strokeColor = [UIColor blueColor];
      renderer.lineWidth = 4.0;            
      return renderer;
  

  //} //返回self.routeLineView; //} //返回nil; }