iBeacon Scanner on iOS (3)

Test iBeacon's iOS Native Location Manager's Events. When App run in background LocationManager will send event about iBeacon Enter or Leave. The problem of this method is you can monitor only 20 locations and the response time is slow. When I turn on the beacon it show Enter in 20~30 seconds. When I turn off beacon it show Leave also in 20~30 seconds. I think there is no way to change this.