title: How to detect with CoreBluetooth when a peripheral disappears?
body: <p>I would like to have a list of ble devices to which my iOS can connect, which refreshes when ble devices appear and disappear.</p>
  
  <p>In order to do that, I created an <code>NSMutableDictionnary* peripheralsAvailable</code>, and everytime <code>- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI;</code> is called by the CBCentralManager, I add the peripheral to the peripheralsAvailable dictionnary (and then update a UITableView). All is OK here.</p>
  
  <p>However I can't find how I can update the dictionnary if a Peripheral "disappear". It seems that I can only add peripherals in my dictionnary when they are detected, but I can't remove one when I shut it down for example.</p>
  
  <p>Could you tell me if I'm missing something?</p>