How to Fix Display Not Updating Issue When Using useEffect() in React Native

Struggling with the `Display Not Updating` issue in React Native when utilizing `useEffect()`? Discover the solution to correct your component rendering and ensure your IP list displays correctly!
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Fixing the Display Not Updating Issue in React Native with useEffect()

React Native’s useEffect hook is a powerful tool for handling side effects in your components. However, sometimes developers encounter frustrating issues that prevent their content from displaying as expected. One common problem is when data seems to populate correctly in the console, but does not show up on screen. In this post, we’ll explore this issue and provide you with a structured solution to ensure your components render as intended.

The Problem: Display Not Updating

You might find yourself in a situation where:

An array of IP addresses is generated and successfully logged.

However, the rendered component does not reflect this array.

Consider the following variables:

[[See Video to Reveal this Text or Code Snippet]]

You are trying to populate ipList upon receiving the subnet from a connected device, yet the display remains unresponsive.

Understanding useEffect and State Management

The Current Approach

In the initial implementation, you had two useEffect hooks:

The first useEffect successfully initializes the component and retrieves connected devices.

The second useEffect attempts to populate the ipList with IP addresses for each pingable address found.

You also had a renderIPList function designed to return the rendered IP addresses:

[[See Video to Reveal this Text or Code Snippet]]

The Key Issue

The main point of concern is how ipList is being populated and referenced. Currently, it’s defined outside the component state, which prevents React from detecting changes and triggering re-renders.

The Solution: Transitioning to State

To ensure that your UI updates appropriately, you need to manage ipList as part of your component’s state. This approach leverages React's built-in state management capability. Here’s how to do it step by step:

Step 1: Initialize State for ipList

Start by defining ipList within the component state using useState:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update ipList Within useEffect

Modify the second useEffect to use setIpList when you are pushing new IP addresses:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Render the Updated List

Finally, instead of invoking renderIPList() from within the useEffect, ensure that it’s called in the component's return statement:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By shifting ipList to be part of the component state using useState, you can now effectively populate and display your list of IP addresses. This ensures that when ipList gets updated, React will re-render the component, reflecting the latest information on the screen.

It’s essential to remember that managing state correctly in React (and React Native) is crucial for responsive interfaces. By leveraging useState alongside useEffect, you can effectively control the flow of data and ensure the user interface updates as expected.

Now, you can confidently troubleshoot similar issues in the future and make sure your components are always in sync with their data!