What to Consider when Integrating BLE in your React Native App
Bluetooth Low Energy (or simply BLE) devices are extremely popular these days. In Stormotion, we have already worked with them in a few projects: one regarding vaping and another — fitness tracking devices.
In this article, we specifically focus on the integration of BLE devices in React Native. Yet, how is this technology different from classic Bluetooth? And what are its key concepts? A brief explanation is below!
📳 Bluetooth Low Energy: Main Concepts and Difference from Classic Bluetooth
We all know what Bluetooth is — a short-range wireless networking protocol to quickly connect devices. Currently, it has 2 versions: Bluetooth Classic and Bluetooth Low Energy.
- Bluetooth Classic is often referred to as just Bluetooth. This technology can support continuous connections and transfer big amounts of data. This may include phone calls, audio streaming, data
- Bluetooth Low Energy is also known as BLE. This is a version of Bluetooth that is adapted to low power sensors and accessories. Such devices don’t require continuous connection but depend on long battery life. They are especially popular in fitness, healthcare, security, home entertainment industries, and beacons.
What are the main terms you need to know when working with this technology? Check below!
Key concepts for BLE 📖
Before you move to BLE integration in a React Native App, it’s important to know how this technology works. We won’t focus on that much but will still refresh some key concepts.
GATT stands for Generic Attribute Profile that defines how BLE-devices transfer data. To make data transfer possible, devices should have a dedicated connection.
BLE-devices are often referred to as peripheral devices, while smartphones, tablets, and other similar gadgets — as central devices. Every peripheral device can have an exclusive connection with one central device at a time, while the central device can be simultaneously connected to multiple peripherals:
Since we’re talking about GATT, let’s take a bit closer look at the server/client relationship:
- From that perspective, a peripheral device is known as the GATT Server that contains data.
- A central device acts as the GATT Client that sends requests to this server.
The Client initiates all the transactions by asking the Server for data. There are 2 ways to transfer data from the Server to the Client: Notifications and Indications.
- Notification is a one-way message. It goes faster since it doesn’t ask the Client whether it has received the message or not.
- Indication describes a system of two-way communication. The Server sends a message ➡️ the Client receives the message and sends a confirmation message back to the Server ➡️ the Server knows that the initial message has reached the Client.
Data transfer itself is based on a few high-level objects: Profiles, Services, and Characteristics.
- Profile is a predefined set of Services.
- Services break data up into logic blocks that consist of Characteristics.
- Characteristic is a single data point, including an array of related data like X/Y/Z values from a 3-axis accelerometer.
Here's an example of how it may look for a fitness tracking device:
If we break down the example above into smaller pieces:
|Services||Blood Pressure Service||Device Information Service|
|Characteristics||Intermediate Cuff Pressure
Blood Pressure Measurement
Blood Pressure Feature
|Manufacturer Name String
Hardware Revision String
Model Number String
But let’s get back to our core topic!
⚙️ 2 Main Libraries for BLE Integration in React Native
As of July 2020, there are 2 libraries that can be used to integrate BLE devices into your React Native application:
❗️ Important note: this article is based on v.7.3.0 of react-native-ble-manager and v.2.0 of react-native-ble-plx
Let’s take a closer look!
React Native BLE PLX is one of 2 libraries you can use to work with this technology. It supports all the key features:
- observing the adapter state of the device’s Bluetooth;
- connecting to peripherals;
- scanning BLE devices;
- discovering services;
- discovering, reading and writing characteristics;
- observing indications & notifications;
- negotiating MTU;
- reading RSSI;
- working in the background mode on iOS;
- turning on the Bluetooth adapter of the device.
Yet, the library doesn’t support the following features:
- peripheral support that enables the communication between phones through BLE;
- creating bonds with peripheral devices;
- working with Bluetooth Classic devices.
The new (2.x) version of the library supports all the latest RN versions starting from 0.60. Yet, you can still use the old version of the library even up to 0.60.5 RN version, but with additional changes
As for OS versions, the library works on iOS 9+ and Android API 19+.
This library is an alternative option you can use to integrate a BLE device in a React Native application.
Despite the explicit list of features isn’t provided, we defined key functionality based on the names of methods. It includes all the features react-native-ble-plx does and a few additional ones like:
- bonding peripherals;
- request connection priority;
- get connected & bonded peripherals.
The latest version of the library supports RN 0.60 and newer. However, the older version of the library can be used with older RN versions:
- React Native 0.40-0.59 is supported until 6.7.X
- React Native 0.30-0.39 is supported until 2.4.3
As for OS versions, this library covers iOS 8+ and Android API 18+.
⚖ react-native-ble-plx vs react-native-ble-manager Comparison
We’ve also made a few comparison tables to cover the main differences between the two libraries:
|🚀 RN version||0.60+||0.60+|
|🍎 iOS version||9+||8+|
|🤖 Android version||19+||18+|
If we take a look at the features, react-native-ble-manager provides a bit more possibilities to developers:
|observing device's Bluetooth adapter state||✅||✅|
|scanning BLE devices||✅||✅|
|making connections to peripherals||✅||✅|
|observing characteristic notifications/indications||✅||✅|
|background mode on iOS||✅||✅|
|turning the device's Bluetooth adapter on||✅||✅|
|communicating between phones using BLE (Peripheral support)||❌||❌|
|bonding peripherals||❌||✅ (Android only)|
|checking if specific peripheral is connected||✅||✅|
|getting bonded peripherals||❌||✅ (Android only)|
|get connected peripherals||❌||✅|
|refresh cache||✅ (Android only)||✅ (Android only)|
|request connection priority||❌||✅ (Android API 21+ only)|
|Written in typescript||✅||✅|
Finally, we can also compare some GitHub stats:
|📊 GitHub Stats (on 12.06.20|
|👩💻 Used by||662||505|
In general, react-native-ble-plx is more popular among developers:
✅ Apps to Test BLE Devices
When developing a React Native mobile app with BLE integration, you'll probably need to test how it really works such devices. Our team used the following apps:
The tools are quite similar and provide many options to test different features of BLE devices.
⚠️ Possible Pitfalls when Integrating BLE Devices
During BLE integration our developers spotted a few pitfalls that can make the development process trickier. Here are our recommendations on how you can make the development go smoother.
# 1: Turn on geolocation 🌍
If you’re developing an Android application, this one will be important. As written in documentation: “Starting from Android API 23+, to access the hardware identifiers of nearby external devices via Bluetooth and Wi-Fi scans, your app must now have the geolocation enabled”.
To check whether geolocation is enabled and turn it on in case its not, we recommend using the react-native-android-location-enabler library.
# 2: Turn on Bluetooth 📳
Obviously, you need to turn on Bluetooth on the device before scanning. For this purpose you may use methods of the mentioned libraries:
# 3: Change device name 📱
When using react-native-ble-plx you may stumble upon a bug when the device name wouldn’t change. That happens because name is cached. This issue is tracked here.
# 4: Keep code quality high 🏆
Finally, here are few general tips to improve code quality:
- Keep all the characteristics and services UUID in one place.
- Avoid magic numbers in characteristic. Instead, use constants.
- Organize the logic structure into 2 separate files:
- one file to keep logic that contains code that is not related to communication with a specific device (e.g. scanning, connection, disconnection);
- another file for code that contains communication with a specific device — discovering services/characteristics, observing notifications/indications, reading/writing characteristics and others.
💡 Takeaways: so Which One to Choose?
Simple but true: the best choice is always the one that matches your needs better than other options. Thus, we’d recommend you to consider things like:
- needed features;
- RN version used in the project;
- OS versions you’d like to cover.
If both libraries suit you from this perspective, we’d choose react-native-ble-plx as it has clearer and better structured documentation.