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Version: v3

Native Handlers

Stream Chat for React Native uses a number of features that require packages that run native code. Stream Chat for React Native also supports Expo, which has it's own set of native packages. To reconcile these differences Stream Chat for React Native is made up of two packages, stream-chat-react-native-core, and either stream-chat-react-native or stream-chat-expo. The non core packages call a function from the core package, registerNativeHandlers, this gives the core package access to different native functions that perform the same task, but are different between Expo and vanilla React Native.

Overriding Handlers#

If desired the native handlers can be overridden. The same function that is called internally to set the handlers can be used to override them, registerNativeHandlers. If the function returns the same type of data as the original function it should seamlessly work with the rest of the SDK. You should look at the default implementation to ensure any override conforms to the appropriate type definition provided by the SDK.

note

This should be done outside of the component lifecycle to prevent unnecessarily re-registering the same handler repeatedly.

Example: Override haptic feedback handler#

Haptic feedback is used in the app to indicate certain presses, and within the image viewer to indicate when zoom limits are hit. If haptic feedback is not desired in your application you can easily remove it by registering a different handler to the function.

import { registerNativeHandlers } from 'stream-chat-react-native-core';

registerNativeHandlers({
triggerHaptic: () => null,
});

Example: Override camera handler#

The takePhoto handler is used to take a picture from the camera and use it as an image attachment while composing a message. By default, SDK uses react-native-image-crop-picker library for this purpose. Although it's possible to replace it with a custom implementation, using react-native-image-picker library in the following example:

import { registerNativeHandlers } from 'stream-chat-react-native-core';
import { launchCamera } from 'react-native-image-picker';

registerNativeHandlers({
takePhoto: () =>
new Promise((resolve, reject) => {
launchCamera(
{
cameraType: 'back',
},
response => {
if (response.errorMessage) {
resolve({ cancelled: true });
return;
}

const photo = response?.assets?.[0];
if (photo?.height && photo.width && photo.uri) {
resolve({
cancelled: false,
height: photo.height,
source: 'camera',
uri: photo.uri,
width: photo.width,
});
}

resolve({ cancelled: true });
},
);
}),
});

Handlers#

There are 13 handlers registered as they interact with different native API packages depending on if the SDK being used on Expo or vanilla React Native.

BlurView#

A component that blurs the view behind it.

React Native: @react-native-community/blur

Expo: expo-blur

compressImage#

An async function that compresses an image and returns the local uri of the compressed image.

React Native: react-native-image-resizer

Expo: expo-image-manipulator

deleteFile#

A function that deletes a file at a given local uri.

React Native: react-native-fs

Expo: expo-file-system

FlatList#

A FlatList component, on Expo the standard React Native component is used, on React Native a modified FlatList better fit for two directional scrolling is used.

React Native: @stream-io/flat-list-mvcp

Expo: react-native

getLocalAssetUri#

A function that gets the local uri of an image or remote asset.

React Native: @react-native-community/cameraroll

Expo: expo-media-library

getPhotos#

A function that returns photos from the camera roll given an offset of after and a number to retrieve, first.

React Native: @react-native-community/cameraroll

Expo: expo-media-library

NetInfo#

A object containing two keys, addEventListener and fetch, which are functions that allow a developer to add listeners to NetInfo or fetch information from NetInfo.

React Native: @react-native-community/netinfo

Expo: @react-native-community/netinfo

pickDocument#

A function to open the document picker and return documents picked from it.

React Native: react-native-document-picker

Expo: expo-document-picker

saveFile#

A function to save a file from a url to local storage.

React Native: react-native-fs

Expo: expo-file-system

SDK#

String identifying which package, stream-chat-react-native or stream-chat-expo, is being used.

React Native: stream-chat-react-native

Expo: stream-chat-expo

shareImage#

A function to provide a given image to the native sharing functionality of the OS.

React Native: react-native-fs & react-native-share

Expo: expo-sharing

takePhoto#

A function that opens the OS specific camera and returns an image when one is taken.

React Native: react-native-image-crop-picker

Expo: expo-image-picker

triggerHaptic#

A function to trigger haptic feedback given the type of haptic force desired.

React Native: react-native-haptic-feedback

Expo: expo-haptics

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