Build a streaming audio app
with React Native
Turntable by Unspash (CCO Public Domain)
Lumpen Radio
WLPN 105.5 FM Chicago
Insurgent radio from Chicago!
low-power
freeform
commercial
Low-Power FM Broadcast Signal (LPFM)
- Made available in 2000
- FCC regulated
- ~100 watts
- ~3.5 mile radius
1.7M listener reach
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Crowdfunded
> $50K raised
Graphic designed by Jeremiah Chiu for WLPN
Bridgeport Studio
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Kickstarter video
React Native iOS App
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For iPad and iPhone
Built to learn
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Children Studying by sof_sof_0000 (CC0 Public Domain)
Stack
- React Native
- Babel
- Webpack
- StreamingKit
- Nicecast
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Languages
Objective-C, Swift, ES6/7
Open Source
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Benefits of React Native
- JavaScript components
- Access platform APIs
- Use Web technology
- Renders views natively
- Faster prototyping
But it looks funny...
"[T]hink of it as a prototype for a different direction of the web."
— James Long
Building it
Radio Mast by stux (CC0 Public Domain)
Getting started
- Learn the basics
- Init project with CLI
- Generate with Yeoman
- Start from seed
Learn the basics
- Complete the Start Developing iOS Apps Tutorial
- Review the iOS Human Interface Guidelines
Init project with CLI
$ npm install -g react-native-cli
$ react-native init my-project
Generate with Yeoman
$ npm install -g yo \
generator-react-native
$ yo react-native
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Start from seed
Kiwi by Security (CC0 Public Domain)
Create an App component
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It should probably...
- Serve as App canvas
- Hold app container View
- Manage screen layout
- Nest components
- Route between Views
Adding a background video
Using react-native-video by Brent Vatne
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Turntable loop video by Scott Schiller, BSD
Install component
$ npm install --save react-native-video
Terminal
Consider shrinkwrapping dependencies
Add to project
- Add .xcodeproj file using the "Add Files to..." dialog shown after context-clicking Libraries.
- Link binary and copy bundle resources as described in the project README.
- Configure project to leverage ES7 Rest/Spread properties.
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Import component
import React from 'react-native';
import Video from 'react-native-video';
export default React.createClass({
render() {
return (
<Video source={{uri: 'turntable-loop-h264-512kbps'}}
style={styles.backgroundVideo}
rate={this.state.rate}
muted={this.state.muted}
resizeMode={this.state.resizeMode}
repeat={this.state.repeat} />
)
});
}
Editor
Style component
import React from 'react-native';
let { StyleSheet } = React;
export default StyleSheet.create({
backgroundVideo: {
position: 'absolute',
top: 0,
left: 0,
bottom: 0,
right: 0
}
}
Editor
Uses
- Loop animations on iOS
- Cast to Apple TV using AirPlay
Create a Native Module
@implementation AudioManager
Module Composition
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Adopt protocols
#import "RCTBridgeModule.h" // or RCTBridge.h
#import "STKAudioPlayer.h"
@interface AudioManager : NSObject
<RCTBridgeModule, STKAudioPlayerDelegate>
@property (nonatomic, strong)
STKAudioPlayer *audioPlayer;
Xcode, Obj-C
Initialize module
- (AudioManager *)init
{
self = [super init];
audioPlayer = [[STKAudioPlayer alloc] init];
[audioPlayer setDelegate:self];
}
Xcode, Obj-C
STK player delegates to class
Define module API
#import "RCTBridge.h"
@implementation AudioManager
RCT_EXPORT_MODULE();
RCT_EXPORT_METHOD(play);
RCT_EXPORT_METHOD(pause);
RCT_EXPORT_METHOD(resume);
RCT_EXPORT_METHOD(stop);
@end
Xcode, Obj-C
Implement API methods
RCT_EXPORT_METHOD(pause)
{
if (!audioPlayer) {
return;
} else {
[audioPlayer pause];
}
}
Xcode, Obj-C
Observe player state
- (void)audioPlayer:(STKAudioPlayer *)player
stateChanged:(STKAudioPlayerState)state
{
switch(state) {
// don't make me do stuff
}
}
Xcode, Obj-C
Use STK for state change handling
Dispatch state changes
#import "RCTEventDispatcher.h"
@synthesize bridge = _bridge;
Xcode, Obj-C
// dispatch on STK state change
switch (state) {
case STKAudioPlayerStatePlaying:
[self.bridge.eventDispatcher
sendDeviceEventWithName:@"AudioBridgeEvent"
body:@{@"status": @"PLAYING"}];
break;
}
Create a Native Module
export class AudioPlayer
Create native interface
import { AudioManager } from 'NativeModules';
export class AudioPlayer
static play() { AudioManager.play(); }
static pause() { AudioManager.pause(); }
static resume() { AudioManager.resume(); }
static stop() { AudioManager.stop(); }
}
Editor
Create component
export default React.createClass({
getInitialState() {
return { status: 'STOPPED' };
}
});
Editor
Handle dispatched events
componentDidMount() {
this.subscription = DeviceEventEmitter.addListener(
'AudioBridgeEvent', (evt) => this.setState(evt)
);
AudioPlayer.getStatus((error, status) => {
(error) ? console.log(error) : this.setState(status)
});
}
Editor
Add UI button
render() {
return (
<View style={styles.appContainer}>
<TouchableOpacity
onPress={this._onPressLogo}
onLongPress={this._onLongPressLogo}>
<Image
style={styles.appLogo}
source={require('image!RadioButton')} />
</TouchableOpacity>
</View>
);
},
Editor
Import ES6 module
import { AudioPlayer } from '../lib/audio';
Editor
For use in your React components
Register button callbacks
_onLongPressLogo() {
AudioPlayer.play();
},
_onPressLogo() {
switch (this.state.status) {
case 'PLAYING':
this.setState({
status: 'PAUSED'
});
AudioPlayer.pause();
break;
}
}
Editor
Provide connection status
Import NetInfo module
import React from 'react-native';
let { NetInfo } = React;
Editor, ES6
Subscribe to changes
export default React.createClass({
componentDidMount() {
NetInfo.isConnected.addEventListener(
'change',
this._onConnectivityChange
);
NetInfo.isConnected.fetch().done((isConnected) => {
this.setState({ isConnected });
});
},
_onConnectivityChange(isConnected) {
this.setState({ isConnected });
}
}
Editor, ES6
Display status
render() {
let message;
if (this.state.isConnected) {
switch(this.props.status) {
// set status message
}
} else {
message = 'Connect to the Internet.';
}
// ...
}
Editor, ES6
Display status
render() {
// ...
return (
<Text style={styles.statusMessage}>
{message}
</Text>
)
}
Editor, ES6/JSX
Animating
Or inbetweening
No, this way!
- No official approach yet
- Said to be "in development"
- Multiple contenders arising
React Tween State
react-motion another option...
Install component
$ npm install --save react-tween-state
Terminal, Bash
Call mixin on mount
export default React.createClass({
mixins: [tweenState.Mixin],
componentDidMount() {
this.tweenState('opacity', {
beginValue: 0,
endValue: 1,
duration: 1000
});
}
}
Editor, ES6
Render with transition
render() {
let transitionStyle = {
opacity: this.getTweeningValue('opacity')
};
return (
<View style={transitionStyle}>
// what to tween
</View>
)
}
Editor, ES6
Using platform APIs
Background playback
@import AVFoundation
- (void)setSharedAudioSessionCategory
{
NSError *categoryError = nil;
[[AVAudioSession sharedInstance]
setCategory:AVAudioSessionCategoryPlayback
error:&categoryError];
if (categoryError) {
NSLog(@"Error setting category!");
}
}
Xcode, Obj-C
And set background mode in Info.plist
First responder
import UIKit
class RootViewController: UIViewController {
override func canBecomeFirstResponder() -> Bool {
return true
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
self.becomeFirstResponder()
UIApplication.sharedApplication().beginReceivingRemoteControlEvents()
}
}
Xcode, Swift
Swap with vanilla controller in AppDelegate
Remote control events
@import MediaPlayer;
- (void)registerRemoteControlEvents
{
MPRemoteCommandCenter *commandCenter;
commandCenter = [MPRemoteCommandCenter sharedCommandCenter];
[commandCenter.playCommand addTarget:self
action:@selector(didReceivePlayCommand:)];
[commandCenter.pauseCommand addTarget:self
action:@selector(didReceivePauseCommand:)];
commandCenter.stopCommand.enabled = NO;
commandCenter.nextTrackCommand.enabled = NO;
commandCenter.previousTrackCommand.enabled = NO;
}
Xcode, Obj-C
Buttons, control panel, lock screen
Audio interruptions
@import AVFoundation
Xcode, Obj-C
See a more detailed explanation on SO
- Stop on device disconnect
- Resume after interruption
Creating an App Icon
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Simplicity is the ultimate sophistication
Leonardo Da Vinci
Considerations
- Using a template
- Automating icon creation
Using a template
iOS 8 App Icon SVG Template for Inkscape
Automating icon creation
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Other considerations
Voice Over
Static resources like image assets take their name from Images.xcassets.
Use spaces to improve aural comprehension.
Localization
Short and sweet.
-
Install react-native-localization module
-
Configure Xcode
-
Create component in app
-
Learn on the Wiki
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Stream location
- Define in Constants.h
- Don't hardcode stream IPs
Debugging
- Shrinkwrap deps, update often
- Try different versions of Node.js
- Cmd+Shift+K in Xcode can help
- Review your build configuration
- Verify Chrome debugger works
Test and submit
Beta testing
- Invite users with iTunes Connect
- App downloads thru TestFlight
- Testers receive emails from Apple
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Submit to App Store
- Get reviewed in beta
- Establish your 1.0
- Release when ready
Deliver sooner
Reflecting on React Native development
You are a pioneer
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Screenshot of the Oregon Trail game
Thought I was too
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Orin_has_died_of_dysentery by Orin Blomberg (CC BY-NC 2.0)
Graphic designed by Jeremiah Chiu for WLPN
Build a streaming audio app with React Native
By Josh Habdas
Build a streaming audio app with React Native
How to create a simple React Native app to stream audio over the web from start to app store submission.
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