CombineCoreBluetooth
CombineCoreBluetooth is a library that bridges Apple’s CoreBluetooth framework and Apple’s Combine framework, making it possible to subscribe to perform bluetooth operations while subscribing to a publisher of the results of those operations, instead of relying on implementing delegates and manually filtering for the results you need.
Requirements:
- iOS 13, tvOS 13, macOS 10.15, or watchOS 6
- Xcode 12 or higher
- Swift 5.3 or higher
Usage
This library is heavily inspired by pointfree.co’s approach to designing dependencies, but with some customizations. Many asynchronous operations returns their own Publisher or expose their own long-lived publisher you can subscribe to. To do something like fetching a value from a characteristic, for instance, you could call the following methods on the Peripheral type and subscribe to the resulting Publisher:
// use whatever ids your peripheral advertises here
let serviceID = CBUUID(string: "0123")
let characteristicID = CBUUID(string: "4567")
peripheral
.discoverCharacteristic(withUUID: characteristicID, inServiceWithUUID: serviceID)
.flatMap { characteristic in
peripheral.fetchValue(for: characteristic)
}
.map(\.value)
.sink(receiveCompletion: { completion in /* ... */ }, receiveValue: { data in
// handle data from characteristic here, or add more publisher methods to map and transform it.
})
.store(in: &cancellables)
The Peripheral type (created and given to you by the CentralManager type) here will filter the results from the given delegate methods, and only send values that match the service and characteristic IDs down to subscribers or child publishers.
Caveats
All major types from CoreBluetooth should be available in this library, wrapped in their own types to provide the Combine-centric API. This library has been tested in production for most CentralManager related operations. Apps acting as bluetooth peripherals are also supported using the PeripheralManager type, but that side hasn’t been as rigorously tested.
