RxBluetoothKit iOS 15 support

There are some changes to the Core Bluetooth API.

CBService
unowned(unsafe) var peripheral: CBPeripheral { get }

CBCharacteristic
unowned(unsafe) var service: CBService { get }

CBDescriptor
unowned(unsafe) var characteristic: CBCharacteristic { get }
iOS 15.X

CBService
weak var peripheral: CBPeripheral? { get }

CBCharacteristic
weak var service: CBService? { get }

CBDescriptor
weak var characteristic: CBCharacteristic? { get }

The changes are detailed describe here in this issue

Solution:

Made below classes' convenience init(…) methods optional convenience init?(…) and only initialize if pass in params required properties(service, characteristic, descriptors) are not deallocated.

RxBluetoothKit

- Characteristic.swift
- Descriptor.swift

Example

    convenience init?(descriptor: CBDescriptor, peripheral: Peripheral) {

        guard let _characteristic = descriptor.characteristic, let _service = _characteristic.service else {
            return nil
        }

        let service = Service(peripheral: peripheral, service: _service)
        let characteristic = Characteristic(characteristic: _characteristic, service: service)
        self.init(descriptor: descriptor, characteristic: characteristic)
    }

Caller sites have been always guard strogeRefeance therefore, added an extra guard for those that are optionally initializable.

Test

Test cases are update and force unwrapped for those optional initializable objects.

Other improvement

Fixed deprecated method signature warnings.

Sep 02 '21 11:09 chamira-at

All committers have signed the CLA.

Sep 02 '21 11:09 CLAassistant

Thank you very much @chamira-at for this PR. A dependency of my project depends on this to unblock me of using the latest Swift version. Looking forward for @robnadin 's review.