SV iOS Meetup Slides: YmsCoreBluetooth and Deep Core Bluetooth
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YMSCoreBluetooth is a block-based API for Core Bluetooth, designed to simplify the development of BLE applications by reducing cognitive load and providing a more straightforward programming model. Released in late 2013, it offers wrapper classes around Core Bluetooth functionalities and has been updated to include improved handling and testability features. The API is inspired by AFNetworking and aims to streamline the connection and interaction processes with BLE devices like the TI SensorTag.
![Design Goals
Hierarchical Object Operation
▸ YmsCoreBluetooth API designed operations in terms of
sending a command to an object
▸ [YMSCBPeripheral connectWithOptions:withBlock:]
▸ [YMSCBPeripheral discoverServices:withBlock:]
▸ [YMSCBService discoverCharacteristics:withBlock:]
▸ [YMSCBCharacteristic writeValue:withBlock:]](https://image.slidesharecdn.com/ymscorebluetoothpresentation-170418055059/85/SV-iOS-Meetup-Slides-YmsCoreBluetooth-and-Deep-Core-Bluetooth-13-320.jpg)
![Deep Core Bluetooth
Learning 2: Unpaired CBPeripheral Identifiers are Cached
▸ There is a fixed size table for mapping MAC addresses to
CBPeripheral identifiers in BT Server
▸ When this table is full, an identifier will be invalidated
▸ To test an identifier, you must call
[CBCentralManager retrievePeripheralsWithIdentifiers:]
▸ iOS 10 made this table really big](https://image.slidesharecdn.com/ymscorebluetoothpresentation-170418055059/85/SV-iOS-Meetup-Slides-YmsCoreBluetooth-and-Deep-Core-Bluetooth-27-320.jpg)
SV iOS Meetup Slides: YmsCoreBluetooth and Deep Core Bluetooth
- 1. YmsCoreBluetooth A block-based API for Core Bluetooth
- 2. YmsCoreBluetooth Core Bluetooth ▸ Bluetooth 4.0 Low Energy (BLE) API ▸ Released 2012 (iOS 5, macOS 10.10) ▸ Delegate-based ▸ Many updates, but very few API changes ▸ Established BLE as the standard Personal Area Network (PAN) for mobile
- 3. Gadgets!
- 5. YmsCoreBluetooth TI SensorTag ▸ IR Temperature Sensor ▸ Humidity Sensor ▸ Gyroscope ▸ Accelerometer ▸ Magnetometer ▸ Barometric Pressure Sensor ▸ Temperature Sensor ▸ Battery/voltage Sensor ▸ Push Buttons BLE! Core Bluetooth!
- 6. Using the Core Bluetooth API felt kinda awkward.
- 7. YmsCoreBluetooth Programming the SensorTag with Core Bluetooth ▸ Delegation pattern for CBCentralManager and CBPeripheral was clumsy to use ▸ 8 sensors = 8 services ▸ Each service had at least two characteristics ▸ Control, Data ▸ A lot of state to keep track of in different places
- 8. In 2013, ObjC blocks were a thing. Why not use them here?
- 9. History YmsCoreBluetooth ▸ Inspired by AFNetworking ▸ Use Obj-C block to process response from a BLE request ▸ Captures state ▸ In-line syntax describes control flow in “one place” ▸ Released late 2013 on GitHub ▸ https://github.com/kickingvegas/YmsCoreBluetooth
- 10. Design Goals YmsCoreBluetooth Design Goals ▸ Get a BLE app up and running fast ▸ Be ready to use in a production app ▸ Use SensorTag as reference model to sanity check above
- 11. Design Goals API Design ▸ Wrapper classes around each Core Bluetooth class ▸ YMSCBCentralManager ▸ YMSCBPeripheral ▸ YMSCBService ▸ YMSCBCharacteristic ▸ YMSCBDescriptor ▸ Subclass off appropriate YMSCB* to personalize YMSCBCentralManager CBCentralManager
- 12. Design Goals Hierarchical Object Operation ▸ Core Bluetooth API designed operations in terms of sender sends message to receiver with matching delegate response ▸ CBCentralManager connects to CBPeripheral ▸ CBPeripheral discovers its CBServices ▸ CBPeripheral discovers the CBCharacteristics for a CBService ▸ CBPeripheral writes to CBCharacteristic ▸ High cognitive load
- 13. Design Goals Hierarchical Object Operation ▸ YmsCoreBluetooth API designed operations in terms of sending a command to an object ▸ [YMSCBPeripheral connectWithOptions:withBlock:] ▸ [YMSCBPeripheral discoverServices:withBlock:] ▸ [YMSCBService discoverCharacteristics:withBlock:] ▸ [YMSCBCharacteristic writeValue:withBlock:]
- 14. Where are we now YmsCoreBluetooth in the Wild ▸ First released on GitHub late 2013 ▸ Last update 2015 ▸ As of 4/12/17 ▸ 498 stars ▸ 128 forks
- 15. Coming Real Soon YmsCoreBluetooth Updates Coming! ▸ Improved YMSCBPeripheral collection handling ▸ Improved BLE scanning API ▸ Improved YMSCBCharacteristic subscription API ▸ Dependency Injection Everywhere ▸ Testability ▸ Decouple from Core Bluetooth objects ▸ Obj-C Nullability & Generics ▸ May 2017
- 17. Deep Core Bluetooth Learning stuff the hard way
- 18. HMM… THAT’S FUNNY, IT WORKS FOR ME. Any developer writing a Core Bluetooth app Deep Core Bluetooth
- 19. Learning 1: Your app doesn’t have direct access to the hardware
- 21. CBCentralManager CBPeripheral App A BT Server BLE Peripheral BLE HW
- 22. CBCentralManager CBPeripheral CBCentralManager CBPeripheral App A BT Server BLE Peripheral BLE HW
- 23. CBCentralManager CBPeripheral CBCentralManager CBPeripheral App A CBCentralManager CBPeripheral CBCentralManager CBPeripheral App B BT Server BLE Peripheral BLE HW
- 24. Deep Core Bluetooth Learning 1: Your app doesn’t have direct access to the hardware ▸ CBPeripheral connection is a logical connection ▸ BT Server manages the physical connection to an actual BLE peripheral ▸ Core Bluetooth state restoration works because of this ▸ Core Bluetooth background execution is decoupled from the app state
- 25. Learning 2: Unpaired CBPeripheral identifiers are cached values
- 26. BLE Peripheral BT Server App advertising MAC: 1235 didDiscoverPeripheral: FRED advertising MAC: 1235 didDiscoverPeripheral: FRED Map MAC to Identifier Map MAC to Identifier Map MAC to Identifier Full advertising MAC: 1235 didDiscoverPeripheral: JANE
- 27. Deep Core Bluetooth Learning 2: Unpaired CBPeripheral Identifiers are Cached ▸ There is a fixed size table for mapping MAC addresses to CBPeripheral identifiers in BT Server ▸ When this table is full, an identifier will be invalidated ▸ To test an identifier, you must call [CBCentralManager retrievePeripheralsWithIdentifiers:] ▸ iOS 10 made this table really big
- 28. Learning 3: If BT Server resets when your backgrounded BLE app is not running, you won’t hear of it.
- 29. BLE Peripheral BT Server App connectPeripheral: connectPeripheral: didConnectPeripheral: didConnectPeripheral: Resets! App terminated in background centralManagerDidUpdateState:
- 30. Deep Core Bluetooth Learning 3: If BT Server resets when your background app is not running, you won’t hear of it ▸ Core Bluetooth background execution is reliant on BT Server always running perfectly ▸ If BT Server resets and your app that supports background execution is not running, you will not receive the centralManagerDidUpdateState: message
- 31. Learning 4: BLE state restoration is a lot of work
- 32. Text Learning 4: BLE state restoration is a lot of work ▸ Restore ServiceUUIDs that were scanned for ▸ You must restore your scan handler ▸ Restore Peripherals that central manager was trying to connect to or had already connected to ▸ You must restore your connection and discovery handlers ▸ Restore Characteristics the central manager was subscribed to ▸ You must restore your notification handlers ▸ Run-time state you keep for a connected peripheral must be restored too!
- 33. Deep Core Bluetooth Core Bluetooth Abstracts BLE ▸ Core Bluetooth is an abstraction API on top of the BLE protocol ▸ Mimics BLE link-layer transactions ▸ Exercises only a sub-set of BLE protocol ▸ Your central never has direct communication with your peripheral
- 34. We ❤ Core Bluetooth