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React Native
The Development Flow
Ritesh Kumar / @ritz078
Lead SDE, Anarock
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No content
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Intro
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• Let’s us build mobile application
• Same Design as React
• True Native Behaviour
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NativeScript
“write once, use everywhere.”
React Native
“learn once, write everywhere”
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Apps built using RN
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react-native init myapp
cd myapp
yarn
yarn build
yarn start
Getting started
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Development
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Type Checking
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https://transform.now.sh
Automate It
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UI Development
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react-storybook
• Isolated UI Development
• Faster updates while
development
• Snapshot testing using
storyshots.
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import React from "react";
import { storiesOf } from "@storybook/react-native";
import CenterView from "./CenterView";
import Button from "components/GenericButton";
import colors from "utilities/colors";
storiesOf("GenericButton", module)
.addDecorator(getStory "=> {getStory()}")
.add("Default", () "=> [
,
,
,
,
,
]);
"// .add ("Another Configuration", () "=>
"//
)
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Isolated UI Development
•Decoupled from the app architecture
•Developed like a library
•Easier testing
•Maintainable
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Images
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Different Pixel Densities
Different Image Resolutions
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Use SVGs
• Use react-native-svg
• Optimize svg using something
like svgo
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import
Svg,
{ Rect }
from "react-native-svg"
export default function() {
return (
)
}
HTML Code React Native Code
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https://transform.now.sh/svg-to-react-native
Automate It
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40-50% size reduction on replacing png with SVG
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Performance
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InteractionManager.runAfterInteractions
InteractionManager.runAfterInteractions(() "=> {
"// ""...long-running synchronous task""...
});
Runs code after the current animations have finished
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requestAnimationFrame
requestAnimationFrame(() "=> {
"// ""...task""...
});
• Runs code before next repaint
• If you are using Animated API, it takes care of the frame updates
for you.
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InteractionManager.runAfterInteractions(() "=> {
"// ""...long-running synchronous task""...
});
requestAnimationFrame(() "=> {
"// ""...task""...
});
VS
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Long Lists
•Don’t use ScrollView
•Use FlatList or SectionList
•They use VirtualizedList internally
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Debugging
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Open Devtools
Refresh on file Change
Update Changed Code
Inspect components &
Touchable areas
FPS Monitor
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Better Debugging (Inspect + Devtools + Redux)
react-native-debugger
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• Use default debugger unless it isn’t useful. It’s fast
• Turn off network monitoring if you don’t need it
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Live Reload
• Reloads the entire page.
• State is lost.
• Updates the changed code.
• State is not lost.
Hot Reloading
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Debugging on Device
adb shell input keyevent 82
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Dev Mode
Tap multiple times to enable
dev mode
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import * as Rx from “rxjs";
this.devModeStream = new Rx.Subject();
this.devModeStream
.bufferWhen(() "=> this.devModeStream.debounceTime(1000))
.filter(x "=> x.length ">= 6)
.subscribe(this.toggleDevMode);
Create a stream
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import * as Rx from “rxjs";
this.devModeStream = new Rx.Subject();
this.devModeStream
.bufferWhen(() "=> this.devModeStream.debounceTime(1000))
.filter(x "=> x.length ">= 6)
.subscribe(this.toggleDevMode);
onClick this.devModeStream.next(event);
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Releases
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beta
beta_native
master
JS only changes
Native + JS Changes
Codepush
Play Store
2.1.x
2.x.0
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Minor (2.5.x)
Major (2.6.0)
All PRs that will go in
CodePush Update
Native release
Beta
Beta
Native
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Release Cycle
Native OTA
Fortnightly Bug Fixes - Instantly
Features - Weekly
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Keep in mind
"react-native-image-picker": "^0.26.7"
Don’t do this or your OTA might break your app.
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Expo
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Getting Started
Scan a QR code
Open a Link
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Online expo editor
https://snack.expo.io/
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Native Features
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Thank You
@ritz078