When it comes to handling Focus Management in React Native for TV apps, developers may find themselves going through five familiar stages (of grief): š«£ š” š š š
Focus management is a unique challenge in TV application development, due to the fragmentation across TV platforms that has led to a variety of focus management techniques. Developers have been forced to create and adopt multiple strategies for managing focus, often juggling platform-specific solutions alongside cross-platform abstractions. The challenge of focus is not only ensuring that focus is handled correctly but handling the platform differences. Android TV and Apple's tvOS have distinct native focus engines which you can read more about in this article written by my colleague @hellonehha.
Originally, TV-specific docs and APIs were part of the main React Native documentation. Now, most TV-specific content has moved to the react-native-tvos project.
react-native-tvos
"react-native": "npm:react-native-tvos@latest"
The react-native-tvos
project is an open source package that provides additions and extensions to the core React Native framework, with a specific focus on supporting Apple TV and Android TV platforms. Most of the changes in this project are centered around handling focus-based navigation on a SmartTV using the D-Pad on the remote control. The project is maintained by (the incredible!) Doug Lowder and is commonly recommended as the primary way to handle focus management in React Native TV applications.
However, like many community-maintained projects, the react-native-tvos
project has evolved based on the needs of developers, and there are now an multiple ways to handle focus. Lets explore the additional components and enhancements to existing components that react-native-tvos
provides:
1. TVFocusGuideView
TVFocusGuideView provides support for Apple's UIFocusGuide API and is implemented in the same way for Android TV, to help ensure that focusable controls can be navigated to, even if they are not directly in line with other controls - As per react-native-tvos.
For example, hereās a grid of 10 Pressable
components rendered inside a TVFocusGuideView
component:
import { TVFocusGuideView } from 'react-native';
const TVFocusGuideViewExample = () => {
const [focusedItem, setFocusedItem] = useState(null);
const renderGridItem = number => (
<Pressable
style={[styles.gridItem, focusedItem === number && styles.focusedItem]}
key={number}
onFocus={() => setFocusedItem(number)}
onBlur={() => setFocusedItem(null)}>
<Text style={styles.gridItemText}>{number}</Text>
</Pressable>
);
return (
<>
<Header headerText="Movies" />
<TVFocusGuideView trapFocusLeft style={styles.grid}>
{[1, 2, 3, 4, 5, 6, 7, 8, 9, 10].map(num => renderGridItem(num))}
</TVFocusGuideView>
</>
);
};
TVFocusGuideView
accepts a few props that help you handle focus:
destinations prop
<TVFocusGuideView destinations={[]}>
With TVFocusGuideView
you can set an array of components to register as ādestinationsā of the TVFocusGuideView
. Lets look at our example:
- Setting the
destinations
prop to be a Ref to item 8(destinations={[item8Ref.current]})
causes the focus to move to item 8 when we initially navigate to theTVFocusGuideView
.
trapFocus prop
<TVFocusGuideView trapFocusUp|trapFocusDown|trapFocusLeft|trapFocusRight />
This prop ensures focus does not escape from the parent component for the given directions. This prop ensures focus does not escape from the parent component for the given directions. Lets look at our example:
- With the
trapFocusLeft
prop you can no longer navigate Left out of the container
autofocus prop
<TVFocusGuideView autoFocus />
When autofocus is set to true, the TVFocusGuideView
will manage focus for you by redirecting the focus to the first focusable child. It also remembers the last focused child and redirects the focus to it on the subsequent visits. If this prop is used with the destinations
prop, the component set by the destinations prop will take precedence. Lets look at our example:
- Without this prop when we moved from the Header component to the
TVFocusGuideView
focus went to the nearest component - item 3 (as per Androids proximity based built-in focus engine) - With the
autofocus
prop it goes to item 1
2. Touchable
With the react-native-tvos
, the Touchable
component's ( TouchableWithoutFeedback
, TouchableHighlight
and TouchableOpacity
) include additional code to detect focus changes and properly style the components when focused. It also ensures that the appropriate actions are triggered when the user interacts with the Touchable
views using the TV remote control.
Specifically, the onFocus
event is fired when the Touchable
view gains focus, and the onBlur
event is fired when the view loses focus. This enables you to apply unique styling or logic when the component is in the focused state that doesnāt come out of the box with core React Native.
Additionally the onPress
method has been modified to be triggered when the user selects the Touchable
by pressing the "select" button on the TV remote (the center button on the Apple TV remote or the center button on the Android TV D-Pad) and the onLongPress
event is executed twice when the "select" button is held down for a certain duration.
3. Pressable
Like Touchable
, the Pressable
component been enhanced to allow it to accept the onFocus
and onBlur
props.
Similar to the āpressed
ā state that is triggered when a user presses the component on a touchscreen, the react-native-tvos
Pressable
component introduces a focused state that becomes true when the component is focused on the TV screen.
Hereās an example when using the Pressable
and Touchable
components from React Native core and they do not accept / execute the onFocus
and onBlur
props:
Using the same Pressable
and Touchable
components from react-native-tvos
they accept and execute the onFocus
and onBlur
props:
4. hasTVPreferredFocus
prop
Some React Native components have the hasTVPreferredFocus
prop, which helps you prioritise focus. If set to true, hasTVPreferredFocus
will force the focus to that element. According to the React Native docs these are the current components that accept the prop:
However, if you are using react-native-tvOS, there are a lot more components that accept this prop:
<View hasTVPreferredFocus />
<Pressable hasTVPreferredFocus />
<TouchableHighlight hasTVPreferredFocus />
<TouchableOpacity hasTVPreferredFocus />
<TextInput hasTVPreferredFocus />
<Button hasTVPreferredFocus />
<TVFocusGuideView hasTVPreferredFocus />
<TouchableNativeFeedback hasTVPreferredFocus />
<TVTextScrollView hasTVPreferredFocus />
<TouchableWithoutFeedback hasTVPreferredFocus />
Lets look at an example:
- Setting the
hasTVPreferredFocus
prop to true forPressable
2 causes focus be onPressable
2 - Changing it to be true when we are on
Pressable
3 causes focus to move toPressable
3
5. nextFocusDirection
prop
The nextFocusDirection
prop designates the next Component to receive focus when the user navigates in the specified direction helping you handle focus navigation. When using react-native-tvos
, this prop is accepted by the same components that accept the hasTVPreferredFocus
prop (View, TouchableHighlight, Pressable, TouchableOpacity, TextInput, TVFocusGuideView, TouchableNativeFeedback, Button
). Lets look at an example:
nextFocusDown={pressableRef3.current}
nextFocusRight={pressableRef5.current}>
- Setting the
nextFocusDown
prop toPressable
3 causes focus to move toPressable
3 when the focus moves down - Setting the
nextFocusRight
prop to Pressable 5 causes focus to move toPressable
5 when the focus moves right
Conclusion
When it comes to handling focus management, there is no one-size-fits-all solution for React Native TV apps. The approach ultimately depends on the specific needs and requirements of your project. While the react-native-tvos
provides a useful cross-device abstractions, you may have to adopt platform-specific solutions to handle common fragmentation issues across SmartTV platforms.
Take the time to explore these various focus management solutions so that you can deliver an intuitive focus handling experience for your users, regardless of the SmartTV platform they are using.
Top comments (1)
this is a great read @anishamalde. I can relate with all 5 griefs :p