React Native Workshop

React Native introductory workshop

Transcript

1. September 2019 Introduction to React Native Victoria Quirante
2. Victoria Quirante I write code at Limenius. We build tailor-made projects, and provide consultancy and formation. And we are very happy users of React and React Native.
3. https://github.com/Limenius/workshop-react-native.git And run git fetch https://speakerdeck.com/victoriaq/react-native-workshop Before we start Please go to where you have cloned the repo of the project
4. Goal of the workshop To be able to estimate how long would it take you to create a first React Native project (and if you would enjoy it) A big part of it is the tooling
5. Roadmap: What is React Native Starting a project Working with Styles Layout Lists Navigation Networking Touching the native side
6. What is React Native?
7. Fundamental premise of React Give me a state and a render() method that depends on it and forget about how and when to render.
8. render() { return ( <div className="App"> <button onClick={this.tick}>Click me!</button> <span>Clicks: {this.state.count}</span> </div> ) }
9. render() { return ( <div className="App"> <button onClick={this.tick}>Click me!</button> <span>Clicks: {this.state.count}</span> </div> ) } render() { return ( <View style={…}> <Button onPress={this.tick}>Click me!</Button> <Text>Clicks: {this.state.count}</Text> </View> ) }
10. render() { return ( <div className="App"> <button onClick={this.tick}>Click me!</button> <span>Clicks: {this.state.count}</span> </div> ) } render() { return ( <View style={…}> <Button onPress={this.tick}>Click me!</Button> <Text>Clicks: {this.state.count}</Text> </View> ) }
11. render() { return ( <div className="App"> <button onClick={this.tick}>Click me!</button> <span>Clicks: {this.state.count}</span> </div> ) } render() { return ( <View style={…}> <Button onPress={this.tick}>Click me!</Button> <Text>Clicks: {this.state.count}</Text> </View> ) } React Native
12. How is this possible Reconciliation Determines what parts of the tree have changed
13. How is this possible Reconciliation Determines what parts of the tree have changed Rendering Actually updates the app
14. How is this possible Reconciliation Determines what parts of the tree have changed Rendering Actually updates the app We can have several renderers
15. React targets Main react-dom react-native Web iOS android
16. React targets Main react-dom react-native Web iOS android But also
17. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom
18. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom react-konsul rax react-native react-blessed react-tvml
19. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom react-konsul rax react-native react-blessed react-tvml React-GL react-vr react-hardware react-fs-renderer react-x11
20. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom react-konsul rax react-native react-blessed react-tvml React-GL react-vr react-hardware react-fs-renderer react-x11 redocx react-titanium React-Gibbon react-pdf react-test-renderer
21. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom react-konsul rax react-native react-blessed react-tvml React-GL react-vr react-hardware react-fs-renderer react-x11 redocx react-titanium React-Gibbon react-pdf react-test-renderer ink react-sketchapp
22. React targets Main react-dom react-native Web iOS android But also react-art react-canvas react-three ReactLiberty react-worker-dom react-konsul rax react-native react-blessed react-tvml React-GL react-vr react-hardware react-fs-renderer react-x11 redocx react-titanium React-Gibbon react-pdf react-test-renderer ink react-sketchapp And more
23. React blessed
24. React blessed
25. React Sketch.app
26. React VR Demo
27. How Native is React Native? JS Thread Business logic & Description of what components to render
28. How Native is React Native? JS Thread Main Thread UI manipulation with native components Business logic & Description of what components to render
29. How Native is React Native? JS Thread Main Thread UI manipulation with native components Business logic & Description of what components to render Bridge
30. How much code can we reuse? Tip: if you develop in one platform, test the app in the other from time to time 70%? 80%? 90%?
31. How to start a project
32. Option 1: expo $ npm install -g expo-cli $ expo init AwesomeProject
33. Option 1: expo Only JS, no iOS or Android code (outside node_modules) If you want to modify native code, $ npm run eject Uses the Expo app to test in real device Meant to have a quick way of trying react-native
34. Option 2: react-native init $ npm install -g react-native-cli $ react-native init AwesomeProject
35. Option 2: react-native init Complete project with native code More control Needed to use things like AppCenter Doesn’t need external tools to publish to the store
36. Getting our hands dirty
37. git clone https://github.com/Limenius/workshop-react-native.git You are supposed to have done this And then yarn install
38. git checkout master react-native run-ios And then Or react-native run-android
39. Debug tools Cmd + d (Cmd + r) ctrl+m / cmd+m
40. Play around Open app/App.js with an editor <Text style={styles.welcome}>Hi there!</Text> Change the text in Try nesting <View> <Text style={styles.welcome}>Hi there!</Text> Amigo </View> Try changing some styles welcome: { fontSize: 100, textAlign: 'center', margin: 10, }, Try placing a console.log(‘hi’) before return(… and see it in Chrome dev tools https://www.slideshare.net/nachomartin/react-native-workshop-react-alicante
41. Familiarize with errors What happens if we… remove a closing tag (</View>) <View style={styles.container}> Hi there! </View> put text not wrapped in <Text/> try to comment a JSX line with // return ( <View style={styles.container}> <Text style={styles.welcome}>Hi there!</Text> </View> <View/> ) have two root elements use wrong properties for styles ( rename flex -> flexo ) remove the words export default
42. Basic components
43. git checkout elements git reset HEAD --hard (To discard your changes)
44. Exercise: Play with the basic components app/App.js
45. Exercise: Build new components Can you build a new component combining others? Ideas: Image with footer (<Text/>), two buttons that display different alerts Can you pass props to that component? Ideas: Pass the text of the footer with props, pass also the image, pass the titles of the buttons Can your build a component with local state? Ideas: Modify the counter to have a “minus 1” button
46. Style
47. No CSS. Everything is JS <View style={{ borderLeftColor: Colors.accent, borderLeftWidth: 9, backgroundColor: Colors.backgroundSection, padding: 18, paddingVertical: 9, }}> No class No dimensions in pixels No things like padding: 19 9 3 1 camelCased Use constants
48. StyleSheet <View style={Styles.headline}> const Styles = StyleSheet.create({ headline: { borderLeftColor: Colors.accent, borderLeftWidth: 9, backgroundColor: Colors.backgroundSection, paddingLeft: 18, paddingRight: 18, paddingTop: 9, paddingBottom: 9, }, })
49. Combination <View style={[Styles.headline, {backgroundColor: 'red'}]}> const Styles = StyleSheet.create({ headline: { borderLeftColor: Colors.accent, borderLeftWidth: 9, paddingLeft: 18, paddingRight: 18, paddingTop: 9, paddingBottom: 9, }, })
50. git checkout styles (To discard your changes) git reset HEAD --hard
51. We want to build this
52. Our first goal is to get this (We will practice layouts in the next section)
53. components/MovieHeader.js height: 210 fontWeight: ‘bold’ fontSize: FontSizes.LargeTitle 48x48, rounded backgroundColor: Colors.highlight color: Colors.text color: Colors.text fontWeight: ‘bold’ border: left, size 9, Colors.accent padding: 9, 18 backgroundColor: Colors.backgroundSection
54. Exercise 1 84x84 Colors.text, bold Container has: border at bottom size 1, Colors.subtleAccent and background is 'white' components/ListItemActor.js
55. Exercise 2 FontSizes.gigantic Colors.background Container has: a background with color: Colors.highlight components/MainHeader.js Image is 40x90 FontSizes.subhead With weight ‘200’ Colors.background
56. Dimensions import { Dimensions, } from 'react-native' const windowSize = Dimensions.get('window') mainImage: { height: windowSize.height /3, width: undefined }, components/MovieHeader.js
57. Dimensions import { Dimensions, } from 'react-native' const windowSize = Dimensions.get('window') mainImage: { height: windowSize.height /3, width: undefined }, Our image height depends on the Height of the window Use sparingly components/MovieHeader.js
58. Dimensions import { Dimensions, } from 'react-native' const windowSize = Dimensions.get('window') mainImage: { height: windowSize.height /3, width: undefined }, Our image height depends on the Height of the window Use sparingly Exercise: Can you make another style dependant of Dimensions? What will happen if the device is rotated? Can you find anything in the documentation to fix it? components/MovieHeader.js
59. Further reading https://www.okgrow.com/posts/react-native-styling-tips https://madebymany.com/stories/a-year-of-react-native-styling-part-1 https://emotion.sh/docs/@emotion/native Explore libraries to do CSS in JS
60. Layouts
61. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap
62. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column' flexDirection: ‘row’ (Default)
63. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column' flexDirection: ‘row’ (Default) main direction cross direction
64. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column' flexDirection: ‘row’ (Default) main direction cross direction cross direction main direction
65. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column’ (Default) ‘flex-start’ ‘flex-end’ ‘center' ‘space-around’ ‘space-between’ flexDirection: ‘row’ (Default) ‘flex-start’ ‘flex-end’ ‘center' ‘space-around’ ‘space-between’
66. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column’ (Default) ‘flex-start’ ‘flex-end’ ‘center' ‘stretch’ ‘baseline’ flexDirection: ‘row’ (Default) ‘flex-start’ ‘flex-end’ ‘center' ‘stretch’ ‘baseline’
67. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘row’ ‘baseline’
68. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flexDirection: ‘column’ alignSelf: ’end’
69. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flex: 1 flex: 0 flex: 0
70. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flex: 5 flex: 2 flex: 3
71. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flex: 0.5 flex: 0.2 flex: 0.3
72. This is flexbox realm flexDirection justifyContent alignItems alignSelf flex alignContent flexBasis flexGrow flexShrink flexWrap flex: 25 flex: 10 flex: 15
73. git checkout layout (To discard your changes) git reset HEAD --hard
74. Our goal
75. app/components/MovieHeader.js
76. app/components/MovieHeader.js
77. 18 Exercise 1 app/components/ListItemActor.js
78. Exercise 2 Hint: create subviews if you need them Optional: can you come up with a different layout for any of our three components? app/components/MainHeader.js
79. Further reading https://facebook.github.io/yoga/docs/getting-started/ Docs: https://github.com/jondot/ReactNativeKatas Very good practice:
80. Lists
81. Lists are important in mobile
82. Naive lists, as in the web export default class Movie extends Component { constructor(props) { super(props) this.state = { movie: movies.find((movie) => movie.name === 'Pulp Fiction') } } render() { return ( <View> <MovieHeader movie={this.state.movie}/> { this.state.movie.actors.map(actor => ( <ListItem key={actor} name={actor} image={actors[actor].image}/> ))} </View> ) } } app/components/Movie.js
83. Naive lists, as in the web export default class Movie extends Component { constructor(props) { super(props) this.state = { movie: movies.find((movie) => movie.name === 'Pulp Fiction') } } render() { return ( <View> <MovieHeader movie={this.state.movie}/> { this.state.movie.actors.map(actor => ( <ListItem key={actor} name={actor} image={actors[actor].image}/> ))} </View> ) } } Important to help the reconciler do its work app/components/Movie.js
84. Exercise git checkout lists Can you build a list of movies in app/components/MovieList.js ? (To discard your changes) git reset HEAD --hard
85. FlatList Highly optimized List component Features: • Scroll loading (onEndReached). • Pull to refresh (onRefresh / refreshing). • Configurable viewability (VPV) callbacks (onViewableItemsChanged / viewabilityConfig). • Horizontal mode (horizontal). • Intelligent item and section separators. • Multi-column support (numColumns). • scrollToEnd, scrollToIndex, and scrollToItem.
86. FlatList render() { return ( <View> <MovieHeader movie={this.state.movie}/> <FlatList data={this.state.movie.actors} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } /> </View> ) } app/components/Movie.js
87. FlatList
88. FlatList What about the keys?
89. FlatList What about the keys? <FlatList data={this.state.movie.actors} keyExtractor={item => item} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } />
90. FlatList What about the keys? <FlatList data={this.state.movie.actors} keyExtractor={item => item} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } />
91. FlatList Scrolleable area <FlatList data={this.state.movie.actors} keyExtractor={item => item} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } /> <MovieHeader movie={this.state.movie}/>
92. FlatList Desired scrolleable area
93. FlatList Desired scrolleable area <FlatList data={this.state.movie.actors} ListHeaderComponent={<MovieHeader movie={this.state.movie}/>} keyExtractor={item => item} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } />
94. FlatList Desired scrolleable area <FlatList data={this.state.movie.actors} ListHeaderComponent={<MovieHeader movie={this.state.movie}/>} keyExtractor={item => item} renderItem={({item}) => <ListItem name={item} image={this.state.actors[item].image}/> } />
95. Exercise Can you use FlatList in app/components/MovieList.js ? git checkout flatlists item => item reminder In this case works as function(item) { return item } git reset HEAD —hard (To discard your changes)
96. Further reading https://facebook.github.io/react-native/blog/2017/03/13/ better-list-views.html Read the docs of the components: FlatList SectionList VirtualizedList
97. Navigation
98. Navigation
99. react-navigation
100. Several options StackNavigator TabNavigator DrawerNavigator Or combine them
101. Several options StackNavigator TabNavigator DrawerNavigator Or combine them
102. Several options StackNavigator TabNavigator DrawerNavigator Or combine them
103. Several options StackNavigator TabNavigator DrawerNavigator Or combine them
104. git checkout navigation yarn install cd ios; pod install Let’s do it (To discard your changes) git reset HEAD --hard If iOS
105. Let’s do it const AppNavigator = createStackNavigator({ Home: { screen: MovieList }, Movie: { screen: Movie }, }, { navigationOptions: { headerTintColor: Colors.accent, headerStyle: Styles.header, } }) const App = createAppContainer(AppNavigator) app/App.js
106. Let’s do it const AppNavigator = createStackNavigator({ Home: { screen: MovieList }, Movie: { screen: Movie }, }, { navigationOptions: { headerTintColor: Colors.accent, headerStyle: Styles.header, } }) const App = createAppContainer(AppNavigator) app/App.js export default class MovieList extends Component { static navigationOptions = { title: 'Movies', } //… app/components/MovieList.js
107. Let’s do it const AppNavigator = createStackNavigator({ Home: { screen: MovieList }, Movie: { screen: Movie }, }, { navigationOptions: { headerTintColor: Colors.accent, headerStyle: Styles.header, } }) const App = createAppContainer(AppNavigator) app/App.js export default class MovieList extends Component { static navigationOptions = { title: 'Movies', } //… app/components/MovieList.js <FlatList data={this.state.movies} ListHeaderComponent={<MainHeader/>} keyExtractor={item => item.name} renderItem={({item}) => <TouchableHighlight underlayColor={Colors.subtleAccent} activeOpacity={0.5} onPress={() => navigate('Movie', {name: item.name})} > <View> <ListItem name={item.name} image={item.image}/> </View> </TouchableHighlight> } /> In render()
108. Let’s do it const AppNavigator = createStackNavigator({ Home: { screen: MovieList }, Movie: { screen: Movie }, }, { navigationOptions: { headerTintColor: Colors.accent, headerStyle: Styles.header, } }) const App = createAppContainer(AppNavigator) app/App.js export default class MovieList extends Component { static navigationOptions = { title: 'Movies', } //… app/components/MovieList.js <FlatList data={this.state.movies} ListHeaderComponent={<MainHeader/>} keyExtractor={item => item.name} renderItem={({item}) => <TouchableHighlight underlayColor={Colors.subtleAccent} activeOpacity={0.5} onPress={() => navigate('Movie', {name: item.name})} > <View> <ListItem name={item.name} image={item.image}/> </View> </TouchableHighlight> } /> In render()
109. Exercise Can you make a navigation transition from Movie to app/components/Actor ? Steps: - Declare the screen in app/App.js - Use a TouchableHighlight to capture onPress in the actors list of <Movie/> - Provide an appropriate title in <Actor/> - Make the actor displayed based on props.navigation.state.params.name Optional: have a look at https://reactnavigation.org/docs/en/stack-navigator.html And tweak the navigation (Ideas: mode modal, add something to headerRight)
110. Networking
111. Networking React-native uses the Fetch API If you already know it, you are all set
112. Let’s do it componentDidMount() { return fetch(baseUrl + '/movies') .then((response) => response.json()) .then((responseJson) => { this.setState({ isLoading: false, movies: responseJson, }) }) .catch((error) => { console.error(error); }) } app/components/MovieList.js
113. Let’s do it git checkout networking yarn install yarn start-server (or npm run start-server) (To discard your changes) git reset HEAD --hard
114. Further reading https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch Docs: https://github.com/mzabriskie/axios Additional libraries:
115. Interactive
116. Our goal
117. Working with state Not specific of React Native, we just use what we know of React
118. Let’s do it git checkout interactive (To discard your changes) git reset HEAD --hard
119. Modify the native side
120. Cases where it is needed Installing packages that have a native side Making our own changes or components Installing assets, such as fonts …
121. Simple case Install this font
122. Let’s do it module.exports = { project: { ios: {}, android: {}, }, assets: ['./assets/fonts/'], }; react-native.config.js git checkout mod-native (To discard your changes) git reset HEAD --hard
123. Let’s do it module.exports = { project: { ios: {}, android: {}, }, assets: ['./assets/fonts/'], }; react-native.config.js npx react-native link git checkout mod-native (To discard your changes) git reset HEAD --hard
124. Assets linked Changes to be committed: (use "git reset HEAD <file>..." to unstage) new file: android/app/src/main/assets/fonts/OleoScript-Bold.ttf new file: android/app/src/main/assets/fonts/OleoScript-Regular.ttf modified: ios/travolta.xcodeproj/project.pbxproj modified: ios/travolta/Info.plist modified: package.json
125. Summary: What is React Native Starting a project Working with Styles Layout Lists Navigation Networking Touching the native side
126. Thanks! @vicqr victoria@limenius.com