How Hot is My Coffee? Sensors, Core Bluetooth, and Swi8!

Evan K. Stone Senior iOS Developer

Cloud City Development // San Francisco

An integrated design and so-ware consultancy specializing in web and mobile apps

There is an explosion.

Not bombs.

Usually doesn’t hurt people.

Very o8en helps people.

This explosion is…

The Internet of Things

Connected devices

Nest. Fitbit. Polar.

Key technology behind it?

Bluetooth Low Energy

What is it?

Not Classic Bluetooth.

A lightweight subset

AKA “Bluetooth Smart”

Why do we care?

It’s exciSng!

It’s fun!

It can be rewarding.

Allows us to interact with physical devices

We can develop iOS apps that communicate with other things

around us!

No cerSficaSon required!

Super Low Barrier for Entry.

TI SensorTag Ambient Light

Digital Microphone

MagneSc Sensor

Humidity

Accelerometer GyroscopeMagnetometer

Ambient Temperature

IR Temperature

$29

What does this mean for us?

The IoT Landscape is changing

Tons of innovaSon going on right now.

Startups

Incubators and Accelerators

They will need you.

Ge]ng started now will help you help them.

Side note:

What about iBeacons?

Subject of another talk!

iBeacons are BLE devices.

Behave differently

They are also fun to work with.

Are handled by a different framework!

Core LocaSon

Ge]ng back to BLE…

Acronym Time!

GAPGeneric Access Profile

Defines how devices adver&se themselves and how they connect

Defines the concept of the Central and the Peripheral

GATTGeneric Aaribute Profile

Defines the way devices transfer data back and forth

Introduces Services and CharacterisScs

You won’t be tested on the acronyms.

Just know they exist.

Roles

We are already used to Client and Server roles

In BLE we have the Central and Peripheral roles

Central

Wants data from a Peripheral

Generally this is your iOS device.

Peripheral

Supplies data.

A device like a heart rate monitor

Becomes an extension of our iOS device, giving it abiliSes it didn’t

have previously

Side note:

An iOS device can be a Peripheral…

…but typically they act as a Central.

The Age of Discovery

For devices to communicate with each other, they must find each

other.

AdverSsing and Discovery

The Peripheral AdverSses

The Central scans and listens

When it finds a Peripheral, the Central can ask to connect.

Kinda like a headhunter on LinkedIn.

Services and CharacterisScs

Services group data

Services contain CharacterisScs

Service

Characteris2c

Characteris2c

Characteris2c

Central connects and discovers Services and CharacterisScs the

peripheral offers

But how?

Core Bluetooth

Apple’s abstracSon over all that Bluetooth gobbledygook.

Encapsulates the funcSonality of the BLE enSSes in framework classes

Remember the four main players?

Central and Peripheral. Service and CharacterisSc.

Everything begins with a CB

Peripheral

CBPeripheral

Central

CBCentralManager

Service

CBService

CharacterisSc

CBCharacterisSc

Side note:

Caveat with Core Bluetooth development

iOS Simulator does not support BLE.

So you have to use a device.

Which devices support BLE?

iPhone 4s and later.iPad 3 and later.

Basic Workflow

Feels very client-server

That’s not an accident.

Workflow:

InstanSate a CBCentralManager

Tell CBCentralManager to scan for Peripherals with Services

we want

When it finds a Peripheral, request to connect

A8er connecSng, find out more about the Peripheral

Read and set characterisScs

Rinse, Lather, Repeat…

Disconnect.

What makes this work?

Enter the UUID.

Enter the UUID.

Standard UUIDs have a 16-bit form.

0x180A

Custom UUIDs have a 128-bit form.

F000AA00-0451-4000-B000-000000000000

What do we mean by Standard and Custom UUIDs?

For example…

Heart Rate Monitor Service0x180D

Heart Rate Measurement CharacterisSc

0x2A37

ExciSng Reading!developer.bluetooth.org

🤓

Custom Service UUIDs

Anything not listed on the standard list.

For example…

IR Temperature SensorF000AA00-0451-4000-B000-000000000000

Where do I find these crazy numbers?

Typically on the vendor website

Or the hardware engineer on your team creates them!

Back to scanning…

CBCentralManager

Core Bluetooth relies heavily on delegates

CBCentralManagerDelegate

CBPeripheralDelegate

Demo Time!

🎉

How Hot is My Coffee?

Side note:

Backgrounding

Yes it’s possible!

Requires a flag in your Info.plist

key: UIBackgroundModesvalue: bluetooth-central

Devices

Many to choose from

New ones appear constantly

TI SensorTaghap://www.S.com/sensortag

LightBlue Bean/Bean+haps://punchthrough.com/bean

Adafruit Feather 32u4 Bluefruit LEhaps://www.adafruit.com/products/2829

TinyCircuitshaps://Sny-circuits.com/

The IoT space is exploding!

More connected devices are being developed every day!

More connected apps are needed every day!

As an iOS developer, you can be on the cu]ng edge of this new fronSer!

Explore!

Experiment!

Connect and Communicate

Core Bluetooth.

Resources

Cloud City DevelopmentBlog hap://cloudcity.io/blog/2015/06/11/zero-to-ble-on-ios-part-one/ hap://cloudcity.io/blog/2015/10/15/developing-ios-app-using-ble-standard/

GitHub haps://github.com/cloudcity/BLECoffee haps://github.com/cloudcity/ZeroToBLE-Part2

Apple's Official Core Bluetooth Docs

IntroducSon to Core Bluetooth Background OperaSon

Best PracSces

Adafruit's IntroducSon to BLE haps://learn.adafruit.com/introducSon-to-bluetooth-low-energy/introducSon

Evan K. Stone

web: h<p://www.cloudcity.io

cloud city blog: h<p://blog.cloudcity.io

blog: h<p://www.interac?velogic.net

twi<er: @interac?vlogic