Develop Reference

React-Navigation added to existing apps

Some background for context...I'm creating a react-native app that will live in it's own repository. This app will be integrated into other web, iOS, and Android apps. I'm currently working with the Android app. This is an existing native app written in Java.
I've "wrapped" it with a super basic React Native app, following the React Native Docs. For testing purposes, to mimic what will end up being the production app, I have a native activity, MainActivity in the Android app, with a button that opens the second activity, ReactNativeActivity which is loads my React Native app. This is working - the React Native app loads. The React Native App has a button that should navigate to a second screen within the React Native app (using react-navigation). When I press that button, instead of navigating to the next screen in my stack, it instead reloads MainActivity from the native Android app. Running the same thing on web there is no issue with navigation, so I know the screens are hooked up right. I'm not new to React Native, but I am new to integrating with existing Native applications.
Edited to add some code as requested
The Navigator and the button are as follows:
// navigator.tsx
import React from "react";
import { NavigationContainer } from "#react-navigation/native";
import { createNativeStackNavigator } from "#react-navigation/native-stack";
import { HomeScreen } from "../screens/Home";
import Demo from "../screens/Demo";
export type NavigationStackParamList = {
HomeScreen: undefined;
Demo: undefined;
};
const Stack = createNativeStackNavigator<NavigationStackParamList>();
export const Navigation = () => {
return (
<NavigationContainer>
<Stack.Navigator>
<Stack.Screen component={Demo} name="Demo" />
<Stack.Screen
component={HomeScreen}
name="HomeScreen"
options={{ title: "Home" }}
/>
</Stack.Navigator>
</NavigationContainer>
);
};
// Demo Screen
const Demo: React.FC<DemoScreenProps> = ({ navigation }) => {
return (
<View style={styles.app}>
<View style={styles.info}>
<Text style={styles.title}>Demo</Text>
<Text>Running on: </Text>
<Text style={styles.platform}>{Platform.OS}</Text>
</View>
<Map />
<Button
onPress={() => navigation.navigate("HomeScreen")}
title="Go to Test Screen"
/>
</View>
);
};
Pressing "Go to Test Screen" above, is what is causing the MainActivity to reload, rather than the correct screen.

Why do I have so many problems refreshing code in Android emulator

So I have just started learning app development with React Native this past week and so I've been getting into using Android studio emulators to run my apps. I've noticed that when I run the apps on the emulator, it doesn't seem to refresh the code properly. For example I made this very simple app while following a tutorial:
import React from 'react';
import { Text, View, Platform } from 'react-native';
import {Button} from 'native-base';
export default class App extends React.Component {
render() {
return (
<View style={styles.container}>
<Text>Testing 12321</Text>
<Button><text>Hello World!</text></Button>
</View>
)
}
}
const styles = {
container: {
flex: 1,
marginTop: 24
}
}
But when I first created it, in the tutorial the instructor forgot to put the Text tag within the button, so when I ran the app I got an error of:
Text strings must be rendered within a <Text> component.
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:4137:14 in <anonymous>
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:4134:2 in createTextInstance
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:15909:12 in completeWork
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:19409:28 in completeUnitOfWork
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:19380:30 in performUnitOfWork
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:19347:39 in workLoopSync
- node_modules\react-native\Libraries\Renderer\implementations\ReactNativeRenderer-dev.js:18997:22 in renderRoot
* [native code]:null in renderRoot
and it keeps going. Then in the tutorial the instructor noticed the mistake and fixed it by adding the tag in the button, but then when he does that, the app refreshed properly and displayed the button but for me I still get this same error. I've noticed this happening quite often with the Emulator, it doesnt like to refresh properly when opening a new app or altering one. I have deleted and recreated the emulator like 5 or more times now to test out different apps. Does anyone have a suggestion of how to fix this? Thanks in advance!

Change your <text> to <Text> as below.
<View style={styles.container}>
<Text>Testing 12321</Text>
<Button><Text>Hello World!</Text></Button>
</View>
Feel free for doubts.

Change the position of a Component on keyboard did show - KeyboardAvoidingView not working - [React Native]

I have my code setup as such:
export default class HomeScreen extends Component {
constructor() {
super();
}
componentDidMount () {
this.keyboardDidShowListener = Keyboard.addListener('keyboardDidShow', this._keyboardDidShow);
this.keyboardDidHideListener = Keyboard.addListener('keyboardDidHide', this._keyboardDidHide);
}
_keyboardDidShow = () => {
console.log('keyboard did show')
}
_keyboardDidHide = () => {
console.log('keyboard did hide')
}
render() {
return (
<Container styles={styles.container} >
<Content styles={styles.content} contentContainerStyle={marginLeft=this.state.marginLeft}>
<Image
style={styles.bgImg}
source={Images.bgImg}
>
</Image>
<Image
style={styles.logo}
source={Images.logo}
>
</Image>
<Text style={styles.slogan}>This is the title</Text>
<Form style={styles.search_form}>
<Item rounded floatingLabel style={styles.search}>
<Label style={styles.search_label}>Where are you headed?</Label>
<Input style={styles.search_input} />
<Button full rounded style={styles.search_btn}>
<Icon name="search"></Icon>
</Button>
</Item>
</Form>
</Content>
</Container>
);
}
}
I want basically the Content component of native-base to avoid the keyboard. I have my logo at the top, the slogan below it and the form at the bottom of the screen by giving some absolute positioning. At this point, the content component moves way up the screen which I don't want. What I want is the logo and the slogan staying right at the top of the screen but the form which is at the bottom of the page; to move up.
Here's what I've researched so far:
Found out that there is actually a component from react native called KeyboardAvoidingView and I played around with it but keeping the Logo, background image and the rest of the content inside the KeyboardAvoidingView made all the content not show in the screen.
Later I found out that the native base component 'Content' itself extends KeyboardAvoidingView, so there was no need to use it in the first place. But I don't think KeyboardAvoidingView is working with my versions of react native and native base.
So at last, I decided that this was a bug and I would use the Keyboard module of the react native instead to do some custom work, which is where I'm at right now, code-wise.
The Question
The console logging inside _keyboardDidShow and _keyboardDidHide are working, which means now I just need to know how to change the style of a component on keyboardDidShow and keyboardDidHide. Any help is appreciated, of course!
I'm really new to react native so any suggestions to better improve my workflow will be taken seriously.

I have already stumbled across the same problem! I'd recommend you save the keyboard width on state, with, for example:
keyboardDidShow = e => this.setState(p => ({ ...p, height: e.endCoordinates.height })
keyboardDidHide = () => this.setState(p => ({ ...p, height: 0 })
then, having this height, you can make your UI depend on that value. After you make sure that is working, in order for it not to jump between positions, use Animated to have a seamless transition between the positions. Hope this helps!

React Native StackNavigator disappearing on re-entry

We are encountering a very bizarre scenario with react-navigation in our React Native application that is only observed on Android (both in the emulator and on physical devices AND for debug builds as well as release builds), but it works fine on iOS.
Context
We have an existing native application, and decided to implement some new screens in React Native as an experiment to see whether it would benefit our development lifecycle.
Our native app has a sidebar menu, and we added a new menu item, that when selected, takes the user into the React Native portion. They can of course navigate back out whenever they want, and later go back into that React Native portion.
Observed problem (Only occurs in Android)
We have identified it relates to the react-navigation library, but we don't know what we're doing wrong.
When the app is first loaded, the user can select the new menu item and the React Native app loads fine, showing its initial route page and with the StackNavigator working fine.
If the user returns to the native portion (either via the back key, or by selecting a different option from the sidebarmenu) and then later opts to return to the React Native portion, then the StackNavigator portion doesn't display. Other React components outside the StackNavigator get rendered. We know it mounts the contained components, as some of them are making API calls and we see those endpoints being queried. It just doesn't render.
Reloading within the emulator will render the app properly again until we navigate out of React Native and then return.
Oddly enough: If we turn on remote JS debugging, it suddenly all works fine.
So our question:
Can anyone spot what we might be missing in how we are using the StackNavigator, that is keeping it from rendering properly? Again: it works fine when the JS debugger is on, making us think that it is not a logic item, but perhaps a timing condition, or some subtle config? Or should we just ditch react-navigation and go to a different navigation library?
Simple reproduction of the issue
Our package.json is:
{
"dependencies": {
"react": "16.0.0",
"react-native": "0.50.4",
"react-navigation": "1.5.2"
}
}
Our React Native entry page (index.js) is:
import * as React from 'react';
import { AppRegistry, Text, View } from 'react-native';
import { StackNavigator } from 'react-navigation';
import TestPage from './TestPage';
AppRegistry.registerComponent('MyApp', () => MyApp);
class MyApp extends React.Component {
public render() {
return (
<View style={{flex:1}}>
<Text>'This text always shows up fine on Android, even on reentry to React application'</Text>
<AccountNavigator />
</View>
);
}
}
const AccountNavigator = StackNavigator(
{
FirstPage: {
screen: TestPage,
navigationOptions: ({ navigation }) => ({
title: 'Test View'
})
},
{
initialRouteName: 'FirstPage'
}
);
The simple test page (TestPage.js) is just:
import * as React from 'react';
import { Text, View } from 'react-native';
export default class TestPage extends React.Component {
render() {
return (
<View style={{flex:1, alignItems: 'center', justifyContent: 'center'}}>
<Text>'If you can read this, then the app is on first load. But return to the native portion and then try to come back to React Native and you will not see me.'</Text>
</View>
);
}
}

Turns out it was a layout setting issue. In our native code, within our React Activity layout XML we had:
<com.facebook.react.ReactRootView
android:id="#+id/ReactRootView
android:layout_width="match_parent"
android:layout_height="wrap_content" />
and the issue was in the "wrap_content" for height which was causing it to render the StackNavigator() as 1 pixel high. No idea why it always happened only on re-entry and not on the first time, nor why the JS debugger would cause the issue to disappear.
Changing layout_height to "match_parent" resolved the issue altogether.

make browsers with react native

I have a mobile site and I want to make an android browser app where I want to open my site.
I have tried and react-native-browser. Something like..
import {
processColor, // make sure to add processColor to your imports if you want to use hex colors as shown below
} from 'react-native';
// at the top of your file near the other imports
var Browser = require('react-native-browser');
class SampleApp extends Component {
render() {
return (
<View style={{paddingTop:20, flex:1}}>
{Browser.open('https://google.com/')}
</View>
);
}
}
But got no success...
I just want to make a browser that opens my mobile site..
Is there any better way of doing this or if someone has any idea how to use react-native-browser ?
Thanks in advance

Looking at the source code, it seems this browser is only available on iOS.

you must search in this web https://js.coach/react-native?search=browser for example https://github.com/d-a-n/react-native-webbrowser

Why are you trying to look for an external library while there is a WebView Component already integrated with react-native itself?
WebView renders web content in a native view. You can use this
component to navigate back and forth in the web view's history and
configure various properties for the web content.
You can just add a WebView and open up the desired web url.
Example
import React, { Component } from 'react';
import { WebView } from 'react-native';
class MyWeb extends Component {
render() {
return (
<WebView
source={{uri: 'https://github.com/facebook/react-native'}}
style={{marginTop: 20}}
/>
);
}
}

You can use https://www.npmjs.com/package/react-native-webbrowser
Install:
npm i react-native-webbrowser --save
Use:
class SampleApp extends Component {
render() {
return (
<View style={{paddingTop:20, flex:1}}>
<Webbrowser
url="https://your-url.com"
hideHomeButton={true}
hideToolbar={true}
hideAddressBar={true}
hideStatusBar={true}
foregroundColor={'#efefef'}
backgroundColor={'#333'}
/>
</View>
);
}
Set all the hide's props to true to make your app display only the site