Darryl and Nolan take a journey of exploration through the world of Bluetooth and Core Bluetooth.
Tweet Shoutouts
@iOhYesPodcast ep.94 you guys talked about the struggle to make income as an indie dev. Is it possible for a newb dev to go indie in 2016?— Kyle Lee (@Kilo_Loco) December 9, 2015
iOhYes: 95 - Great non technical episode of @iOhYesPodcast with @jaimeejaimee I'll start my #tinychallenges in Jan https://t.co/rR2W5udvGb— You can call me Joe (@mokagio) December 10, 2015
.@iOhYesPodcast Got to listen to the podcast on my way to the tvOS tech talk. Love the tiny challenges concept. @jaimeejaimee— Jeremiah Jessel (@JCubedApps) December 10, 2015
@iOhYesPodcast Sorry to keep you gentlemen in suspense. Ep #93 was great — motivation, conference philosophy, and plenty of tips!— Greg Heo (@gregheo) December 11, 2015
@iOhYesPodcast @dh_thomas Thanks for the ep #95 pick! I enjoyed the non-tech talk — like refactoring your life rather than your code ;)— Greg Heo (@gregheo) December 11, 2015
@jaimeejaimee @iOhYesPodcast great interview! Thank you Jaimee for being so open about your life, I know I learned from #tinychallenges— Dale Fairclough (@faircoder) December 12, 2015
Discussion - News we missed
Swift is Open Source!
Apple starting to accept pull requests (notably the removal of C-style for loops)
Docs are also open, and a call has been made for translations
Apple to remove headphone jacks??
Audio over Lightning?
Bluetooth
Discussion - Core Bluetooth
Bluetooth’s Background
Invented by Ericsson in 1994 as a wireless alternative to RS-232 serial interfaces
IEEE 802.15.1 (Bluetooth) part of IEEE 802.15 (Personal Area Network: PAN) within IEEE 802 (Local and Metropolitan Area Networking, LAN & MAN) Wikipedia Link
The name is a nod to King Harald "Blåtand" Gormsson (Bluetooth is an anglicanized version of "Blåtand"). King Bluetooth is said to have united the Danish tribes into a single kingdom.
The logo is a bind rune forming the initials H. B. (sort-of)
Versions
1.2
1 Mbps data rate, > 80 kbps application throughput
Probably the first version considered “viable.”
2.0 + EDR
3 Mbps data rate, > 80 kbps application throughput
3.0 + HS
24 Mbps data rate, but not really: The connection is negotiated over a BT link, but 802.11 is used for data transfer
4.0 (Classic and HS) & 4.0 LE (Branded as Bluetooth Smart)
24 Mbps data rate, but not really: See 3.0 + HS and LE has extremely low throughput by design (like less than 100 kbps)
Bluetooth LE
Totally new protocol specifically designed for low energy consumption and simplified communications
Peripheral devices can implement just LE, just Classic or both
Bluetooth LE and Core Bluetooth
Core Bluetooth provides a layer of abstraction over the GATT profile (Generic Attribute Profile)
Peripherals are “servers”
Centrals are “clients”
Peripherals serve one or more Service(s)
Services have Characteristics (can be thought of as attributes or properties)
Characteristics have a value, which may be readable, writable or notifiable
Using CBCentralManager
Instantiate the manager and then check for availability (implement the -centralManagerDidUpdateState: delegate method and check for PoweredOn state
Scan for services with service UUIDs you provide using -scanForPeripheralsWithServices:options:
When peripherals are discovered, the -centralManager:didDiscoverPeripheral:advertisementData:RSSI: delegate method will be called
Connect to a peripheral using -connectPeripheral:options:, which in turn will call the delegate’s -centralManager:didConnectPeripheral: method.
At this point, you can start using the peripheral directly. (And get responses through the CBPeripheralDelegate protocol)
Discover services with -discoverServices:, which will result in the delegate’s -peripheral:didDiscoverServices: method being called
Similarly, discover characteristics of a service using -discoverCharacteristics:forService:, from which you can expect a -peripheral:didDiscoverCharacteristicsForService:error: message
Depending on the peripheral’s configuration, values for a characteristic can be read, written to or monitored for changes (notified)
Characteristic values are expected to be small. (Like 20 bytes or smaller.) If you need to send larger payloads, it’s possible to roll-your-own streaming protocol atop characteristics.
I don’t really recommend this, but it’s a fairly common approach
I suspect some of this comes from the legacy of BT being treated as a dumb serial link
Apple has recognized this trend and in recent versions of iOS/OS X, they have tried to accommodate higher throughput by negotiating higher MTUs when possible. They even demonstrate how this can be done in one of their WWDC sessions.
Picks
Nolan
Star Wars Trilogy: Despecialized Edition
Star Wars Machete Order
Darryl
WWDC 2012 Session 703 - Core Bluetooth 101
WWDC 2012 Session 705 - Advanced Core Bluetooth
WWDC 2012 Session 701 - iOS Accessories
WWDC 2013 Session 703 - Core Bluetooth
WWDC 2013 Session 307 - What's New in Core Location
WWDC 2014 Session 708 - Taking Core Location Indoors
WWDC 2014 Session 713 - What's New in iOS Notifications
