取消 BLE 外设连接 iOS 后无法重新连接

Question

In my project I was successful to connect to a Bluetooth LE peripheral and read CBCharacteristic value from that device. I am facing an issue. I need to disconnect the peripheral and reconnect the device again if user wishes.

I am using the following steps.

1. For Disconnecting : I am calling centralManager?.cancelPeripheralConnection(peripheral) . This call is completed successfully calling delegate func centralManager(central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: NSError?)

2. To Reconnect : I start scanning for peripherals, as I did when the app launched centralManager!.scanForPeripheralsWithServices(nil, options: nil)

But this call never calls the delegate func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) where I try to connect the BLE discovered peripheral.

My question is what is the best practice to disconnect a BLE peripheral and reconnect it again in iOS. Am I doing anything wrong?

Answer 1

Thats not the right way to re-connect to BLE.

Per Apple Documentation :

Reconnecting to Peripherals

Using the Core Bluetooth framework, there are three ways you can reconnect to a peripheral. You can:

1. Retrieve a list of known peripherals—peripherals that you've discovered or connected to in the past—using the
   retrievePeripheralsWithIdentifiers: method. If the peripheral you're looking for is in the list, try to connect to it. This reconnection
   option is described in Retrieving a List of Known Peripherals.
2. Retrieve a list of peripheral devices that are currently connected to the system using the retrieveConnectedPeripheralsWithServices: method. If the peripheral you're looking for is in the list, connect
   it locally to your app. This reconnection option is described in
   Retrieving a List of Connected Peripherals.
3. Scan for and discover a peripheral using the scanForPeripheralsWithServices:options: method. If you find it, connect to it. These steps are described in Discovering Peripheral Devices That Are Advertising and Connecting to a Peripheral Device After You've Discovered It.