iOS: Bluetooth LE peripheral no longer updating after coming back into range

Question

I have written an iOS app that reads data from a TI SensorTag. Following the advice Apple provides in the "Core Bluetooth Programming Guide", I have subscribed to the service characteristic's value by calling the peripheral object's setNotifyValue:forCharacteristic: method. Periodically, the peripheral calls the peripheral:didUpdateValueForCharacteristic:error: method to inform me the value of interest has changed, and I read it, as described in the documentation.

When I move the iOS device a certain distance from the SensorTag, the didUpdateValueForCharacteristic method stops being called (apparently) because the two are "out-of-range". But when I move the devices back "in-range", updating does not resume. Somehow, my "peripheral" object no longer represents the real peripheral device.

What steps can I follow to 1) programmatically "notice" the peripheral is no longer "valid", and 2) re-connect to my device without user intervention?

Thanks!

--Bill

Answer 1

When your peripheral disconnects, the centralManager:didDisconnectPeripheral:error callback is called. In this callback you can immediately start a connection request to the same peripheral with the connectPeripheral:options: method. This request will stay active until the connection happens. It doesn't require any user interaction.