10 React Native Styling Best Practices

React Native is a popular framework for building cross-platform mobile applications. When it comes to styling React Native applications, there are a few best practices to keep in mind. In this article, we’ll discuss 10 of those best practices.

1. Use Flexbox

Flexbox is a layout model that gives you control over how your React Native components are laid out on the screen. With Flexbox, you can specify the direction of the items in a container, whether they should wrap if they don’t fit, and the order of the items.

This makes it much easier to create complex layouts with React Native than it would be with other methods, such as CSS grid or floats. In addition, Flexbox is well-supported by React Native and works across platforms.

If you’re not familiar with Flexbox, there are plenty of resources available to help you learn, including the React Native documentation. Once you’ve got a handle on Flexbox, you’ll be able to create React Native layouts that are both responsive and easy to maintain.

2. Avoid using the style attribute

The style attribute is a way of applying inline styles to React components. In other words, the style attribute is used to add CSS styles to React elements.

While there are some advantages to using the style attribute, such as being able to apply different styles based on props or state, it also has some drawbacks.

One of the biggest drawbacks is that it can make your code difficult to read and maintain. This is because when you use the style attribute, all of the styles are applied inline, which can make your JSX markup cluttered and hard to decipher.

It’s also worth noting that the style attribute only supports camel-cased CSS properties, which means you can’t use kebab-case (e.g. background-color) or snake-case (e.g. font_size) properties.

So, what’s the alternative?

Instead of using the style attribute, you can use the StyleSheet API. The StyleSheet API is a way of defining CSS styles in JavaScript. These styles are then applied to React components via the styleName prop.

Using the StyleSheet API has a number of benefits over using the style attribute. For starters, it makes your code easier to read and maintain because the styles are not applied inline.

It also allows you to use kebab-case and snake-case CSS properties, which can be helpful if you’re working with a team of developers who are used to writing CSS in those formats.

Finally, it’s also more performant because the styles are compiled ahead of time instead of being parsed and applied at runtime.

3. Understand how React Native handles stylesheets

React Native uses JavaScript to style components, which is different from how CSS works. In order to get the best performance possible, React Native compiles the stylesheets into a single JavaScript file instead of using separate files for each component like traditional CSS.

This means that you need to be careful about how you structure your stylesheets, and make sure that you’re not creating any unnecessary duplication. For example, if you have a global stylesheet that’s imported by every component, make sure that you only include the styles that are actually used by those components.

Additionally, take advantage of React Native’s built-in support for media queries and other responsive design techniques to optimize your stylesheets for different screen sizes.

4. Use StyleSheet.create to define your styles

When you use the StyleSheet.create method to define your styles, it produces a minimal set of CSS rules that are passed down to the renderer. This means that your app will have less style declarations and will be faster.

It also means that you can take advantage of React Native’s built-in optimizations, such as dead code elimination and minification, which will further reduce the size of your app.

5. Use Platform-Specific Styles

Different platforms have different conventions for how users expect UI elements to look and behave. For example, on iOS, buttons are typically round with a shadow, while on Android, they’re rectangular with a ripple effect.

If you want your app to feel native on each platform, it’s important to style UI elements according to the platform’s conventions. React Native makes this easy to do with the StyleSheet.Platform API.

For example, let’s say you have a button component that you want to style differently on iOS and Android. You can use the StyleSheet.Platform API like this:

“`
const styles = StyleSheet.create({
button: {
…Platform.select({
ios: {
backgroundColor: ‘red’,
},
android: {
backgroundColor: ‘blue’,
},
}),
},
});
“`

This will render the button with a red background on iOS and a blue background on Android.

6. Use Absolute Positioning Carefully

If you use absolute positioning to style a component, the component will be completely detached from the normal flow of the document. This means that if the component is styled using relative positioning, it will not take up any space in the document and other elements will act as if it’s not there.

This can cause problems because if the component is styled using percentages, the percentage will be based on the size of the containing element, not the size of the document. This can lead to unpredictable results.

It’s generally best to avoid using absolute positioning unless you’re confident that you understand how it works and you’re sure that it won’t cause problems for other elements in the document.

7. Don’t use marginTop and friends

When you set a marginTop on an element, what actually happens is the element gets rendered with that margin, but then the page’s content height doesn’t change. So if you have a long list of items and each one has marginTop, they’ll eventually start to overlap because there isn’t enough room for all of them.

Instead, use paddingTop on the container element. This will add the desired space without affecting the page’s content height.

8. Use PixelRatio for Density Independence

PixelRatio is a library that provides a wrapper around React Native’s built-in Dimensions API. The main benefit of using PixelRatio is that it automatically scales your UI elements based on the device’s pixel density, making them appear crisp on any screen size.

This is especially important for React Native because, unlike web browsers, there is no standard viewport size for mobile devices. So, if you were to hard-code your UI element sizes in pixels, they would likely appear too small on high-density screens and too large on low-density screens.

PixelRatio is easy to use and can be imported like so:

import { PixelRatio } from ‘react-native’;

Once you have PixelRatio available in your component, you can use it to scale your UI element sizes. For example, let’s say you want to display an image that is 100px by 100px on a low-density screen. You would use the following code:

style={{
width: PixelRatio.getPixelSizeForLayoutSize(100),
height: PixelRatio.getPixelSizeForLayoutSize(100),
}}
source={require(‘./my-image.png’)}
/>

This code will automatically scale the image to the correct size for the device’s pixel density.

9. Use Dimensions to Get Screen Size

If you’re using a library like React Native Elements, you’ll want to make use of their responsive design system. In order to do that, you need to know the screen width and height so that you can scale your components accordingly.

The other reason why Dimensions is important is because on Android, React Native doesn’t support the use of percentage values for dimensions. This means that if you want to have a component that’s 50% of the screen width, you need to use Dimensions to get the screen width, and then multiply it by 0.5.

Overall, using Dimensions is the best way to ensure that your React Native app looks great on all devices.

10. Use Colors in a Cross-Platform Way

Different operating systems have different default colors for their UI elements. For example, on iOS the default color for buttons is blue, but on Android it’s gray. If you hard-code colors in your stylesheets then your app will look out of place on one platform or the other.

Instead, you should use the platform-specific color constants that are available in React Native. For example, on iOS you would use the color constants from “react-native/Libraries/Appearance/Constants.h”, and on Android you would use the color constants from “react-native/android/support/v4/graphics/ColorUtils”.

Using these platform-specific color constants ensures that your app looks consistent on all platforms, which is important for creating a polished user experience.