Not receiving response from discoverServices

[andr3a88-amk]

Hi, I am experiencing an issue with my connection flow when using the library. Occasionally, the code gets stuck after calling discoverServices, and the process ends with a peripheral disconnection error (the peripheral has a timeout of 5 minutes)

Below is the relevant part of my code:

if peripheral.state != .connected {
    logger.debug("📶 Peripheral not connected. Connecting...", subsystem: Self.tag)
    try await centralManager.connect(peripheral, options: options)
}
logger.debug("📶 Connected to peripheral \(peripheral.cbPeripheral.description)", subsystem: Self.tag)

try await peripheral.discoverServices(sensorServiceIds.map { $0.cbUUID })
logger.debug("💡 Discover services for peripheral \(peripheral.identifier)", subsystem: Self.tag)

The logs indicate that discoverServices does not return the expected services. The connection seems successfully initiated (state = connected), but the discoverServices call appears to hang and does not return the services. This mainly occurs when peripheral.state is connected

17:14:09 📶 Connected to peripheral <CBPeripheral: 0x300d880d0, identifier = 24CF3D10-C283-018D-FB02-5BC4B0A024DE, name = Respiro, mtu = 247, state = connected>
17:19:42 didDisconnectPeripheral <CBPeripheral: 0x300d880d0, identifier = 24CF3D10-C283-018D-FB02-5BC4B0A024DE, name = Respiro, mtu = 23, state = connecting> | isReconnecting false | The connection has timed out unexpectedly

Could this be a bug in the library, or is there something I might be missing in the connection flow?
Are there any known issues with discoverServices in similar scenarios?

[manolofdez]

Hi,
I am not aware of any issues with discoverServices. If you set a breakpoint in PeripheralDelegate's line 34, does it get hit?

[andr3a88-amk]

Hi @manolofdez, sorry for the delay. At the moment i can't figure out the issue.

The only time when it happens is after a peripheral restore or after a consequent peripheral disconnection (caused by The connection has timed out unexpectedly) and reconnection. Then if I use the peripheral restored/reconnected sometimes i got Service not found and sometimes no responses from the peripheral.

[nonameplum]

@andr3a88-amk could it be connected to this issue https://forums.developer.apple.com/forums/thread/742497 ?

[andr3a88-amk]

@nonameplum yes is possible, but from my logs I cannot see a peripheral with same UUID but different memory address.

When a peripheral is restored i use the method retrievePeripherals, to get a fresh instance. but right after the restoration i have a disconnection:

let peripheralsRetrieved = centralManager.retrievePeripherals(withIdentifiers: [cbPeripheralRestored.identifier])

08:37:38  Restored peripheral received: <CBPeripheral: 0x302fb6970, identifier = B19706B8-D5DE-BE36-560C-E909590D20E9, name = "", mtu = 247, state = connected>

08:37:39 didDisconnectPeripheral <CBPeripheral: 0x302fb6970, identifier = B19706B8-D5DE-BE36-560C-E909590D20E9, name = "" , mtu = 23, state = connecting> | isReconnecting false | The connection has timed out unexpectedly.

[andr3a88-amk]

Hi @manolofdez, I have a question about the behavior of connect method.

Does this method return immediately after initiating the connection request (after the call), or does it stay in an await state until the connection is fully established?

try await centralManager.connect(peripheral, options: nil)