React Native Background Timer

Introduction

React Native Background Timer provides a solution for running timers in the background of your React Native apps. It leverages the native capabilities of iOS and Android platforms to ensure accurate timing even when the app is in the background or the device is locked. This is particularly useful for applications that require periodic background tasks, such as scheduling notifications, syncing data, or updating location-based information.

Installation

To use React Native Background Timer in your project, you need to install the package using npm or yarn. Open your terminal and run the following command:

Once the installation is complete, you need to link the package with your native project using the React Native CLI :

Usage

Cross Platform

React Native Background Timer is designed to work seamlessly across both iOS and Android platforms. It provides a consistent interface for running timers in the background, regardless of the operating system.

iOS

When using React Native Background Timer on iOS, no additional steps are required. The library leverages the background execution capabilities provided by the iOS operating system. You can directly use the background timer in your React Native code without any extra configuration.

Android

For Android, some additional steps are necessary to enable background execution. You need to modify the AndroidManifest.xml file in your project. Open the file located at android/app/src/main/AndroidManifest.xml and add the following lines inside the <manifest> tag :

These permissions are required to wake up the device and prevent battery optimizations from interfering with the background timer.

Obsolete

It's important to note that starting from React Native version 0.65, the usage of the react-native-background-timer package has been deprecated. The recommended approach for implementing background tasks in React Native is to use the react-native-background-fetch package. Therefore, it is advisable to migrate to the react-native-background-fetch package for new projects or when updating existing projects.

By adopting the recommended package, you can take advantage of the latest features and improvements in background task management in React Native.

Setting Up Our Project

To start using React Native Background Timer in your project, follow these steps:

• Create a new React Native project using the react-native init command.
• Install the React Native Background Timer package by running npm install react-native-background-timer or yarn add react-native-background-timer.
• Link the package to your project using the command react-native link react-native-background-timer.

Coding the Layout

In your main component file, import the necessary components from React Native and React Native Background Timer :

Next, create a functional component called BackgroundTimerScreen :

Adding State and a useEffect Hook to Start/Stop the Timer

Inside the BackgroundTimerScreen component, add the following code to define a state variable and a useEffect hook :

This code sets up a state variable called a timer and uses a useEffect hook to start or stop the background timer based on its value. It also cleans up the timer when the component unmounts.

Define the startTimer Function

Next, define a function called startTimer that will start the background timer :

Format the Time

Inside the startTimer function, you can add code to format the time in hours, minutes, and seconds. Here's an example of how you can do it:

This function takes the total time in seconds as an argument and returns a formatted string representing the time in the format HH:MM.

Rendering Out the Time

Now, you can update the return statement in the BackgroundTimerScreen component to display the time :

In this code, a Text component is used to display the formatted time. The TouchableOpacity component is used to start the timer when pressed.