Indicates whether the manager automatically updates its internal service objects when a remote device reconnects (True), or you want to manually perform a new service discovery operation to obtain new, valid internal service objects (False).
This property only affects OS X and iOS.
In those platforms, when a previously-discovered remote device disconnects, the internal objects that represent its services in your Bluetooth manager become invalid. When the remote device reconnects, the run-time platform generates new internal objects to represents the services of that remote device.
By default, any instance of TBluetoothGattService, TBluetoothGattCharacteristic or TBluetoothGattDescriptor that belonged to that remote device becomes invalid, and you must perform a new service discovery to obtain new objects that you can use. Change the value of UpdateOnReconnect to True if you want your manager to automatically update your existing objects when a device reconnects so that you do not need new objects.
Other platforms do not need new instances of TBluetoothGattService, TBluetoothGattCharacteristic or TBluetoothGattDescriptor when remote devices reconnect.
TBluetoothLEDevice.UpdateOnReconnect
原文：http://www.cnblogs.com/cb168/p/5151524.html