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React Native in a
native world
Neil Kimmett
Feb 20, 2019 @ DeveloperWeek
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React Native in a
native world
Neil Kimmett
Feb 20, 2019 @ DeveloperWeek
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@neilkimmett
hello
" from London
mobile dev for 10 years
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ClassPass is the world’s leading marketplace for
studio fitness, gym and wellness
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ClassPass is the world’s leading marketplace for
studio fitness, gym and wellness
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ClassPass is the world’s leading marketplace for
studio fitness, gym and wellness
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4
ClassPass is the world’s leading marketplace for
studio fitness, gym and wellness
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What is React Native?
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How do we use
React Native at ClassPass?
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Should you use React Native
in your app?
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What is React Native?
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What is React Native?
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10
React
declarative
component-based
UI library
is a
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React is declarative
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React is declarative
Describe what you want,
not how to create it
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React is declarative
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React is declarative
View = (State)
f
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React is declarative
State
“name”
[ 1 , 2 , 3 ]
✓
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React is declarative
State f
“name”
[ 1 , 2 , 3 ]
✓
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13
React is declarative
State f
“name”
[ 1 , 2 , 3 ]
✓
View
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14
React is not imperative
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14
React is not imperative View
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14
React is not imperative View
[ 1 , 2 , 3 ]
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14
React is not imperative
f
View
[ 1 , 2 , 3 ]
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14
React is not imperative
f
View
[ 1 , 2 , 3 ]
f
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14
React is not imperative
f
“name”
View
[ 1 , 2 , 3 ]
f
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14
React is not imperative
f
“name”
View
[ 1 , 2 , 3 ]
f
State
✓
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14
React is not imperative
f
“name”
✗
View
[ 1 , 2 , 3 ]
f
State
✓
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React is declarative
State f
“name”
[ 1 , 2 , 3 ]
✓
View
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React is component based
App
Profile
Image Text
…
…
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React is component based
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React is component based
![]()
{this.state.name}
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render() {
return (
![]()
{this.state.name}
)
}
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React is component based
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class Profile extends Component {
render() {
return (
![]()
{this.state.name}
)
}
} 19
React is component based
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React
declarative
component-based
UI library
is a
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What is React Native?
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React Native
JavaScript framework for
writing native mobile
apps using React
is a
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Why
React Native?
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Why React Native?
Cross-platform
You probably have web developers on
your team, writing your native app in
JavaScript means they can contribute.
Create two mobile apps
from one codebase.
Hot reloading reduces length of
iteration cycles because you don’t have
to wait for compilation.
Better developer
experience
JavaScript
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A React Native app
is a real mobile app
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React Native rendering
Profile
Image Text
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React Native rendering
Profile
Image Text
iOS UIImageView UILabel
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React Native rendering
Profile
Image Text
iOS UIImageView UILabel
ImageView TextView
Android
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React Native rendering
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React Native rendering
iOS Android
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How do we use
React Native at ClassPass?
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Mobile at ClassPass
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Mobile at ClassPass
- iOS app started in 2014
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Mobile at ClassPass
- iOS app started in 2014
- Android app started in 2015
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Mobile at ClassPass
- iOS app started in 2014
- Android app started in 2015
- React Native introduced in 2017
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Mobile at ClassPass
- iOS app started in 2014
- Android app started in 2015
- React Native introduced in 2017
- around 15 mobile developers
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monorepo
classpass-mobile
android
ios
react-native
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monorepo
7%
15%
29%
13%
36%
Java Kotlin Swift Objective-C JavaScript Scripts
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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Venue detail
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Venue detail
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Venue detail
- long, heterogenous content
- limited interactivity
- existing Objective-C implementation
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Venue detail
existing iOS container
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Venue detail
existing iOS container
existing iOS view
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Venue detail
existing iOS container
existing iOS view new React Native view
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Venue detail
existing iOS container
existing iOS view new React Native view
switched using server
side feature flag
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Venue detail
existing iOS container
new React Native view
switched using server
side feature flag
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Venue detail
existing iOS container
existing iOS view new React Native view
switched using server
side feature flag
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class VenueDetailViewController {
init(venue: Venue)
var view: UIView {
if featureFlags.reactNativeVenueDetail {
return reactNativeView
} else {
return legacyView
}
}
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Venue detail
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Venue detail VenueDetailViewController
reviewsTapped
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Venue detail VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
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VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
onPressIn
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VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
onPressIn
{
'fn':…
}
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VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
onPressIn
{
'fn':…
}
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VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
onPressIn
{
'fn':…
}
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VenueDetailViewController
reviewsTapped
RNVenueBridgeModule
reviewsTapped
onPressIn
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let vc = VenueDetailViewController(venue: …)
present(vc)
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Encapsulated and isolated
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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No content
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iOS Android
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Navigation in
React Native
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https://medium.com/@pavsidhu/whats-happening-with-navigation-in-react-native-c193535888c3
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JavaScript Navigation
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JavaScript Navigation
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JavaScript Navigation
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JavaScript Navigation
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JavaScript Navigation
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JavaScript Navigation
thin native shell
navigation in JS
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JavaScript Navigation Native Navigation
thin native shell
navigation in JS
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JavaScript Navigation Native Navigation
thin native shell
navigation in JS
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JavaScript Navigation Native Navigation
thin native shell
navigation in JS
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JavaScript Navigation Native Navigation
thin native shell
navigation in JS
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JavaScript Navigation Native Navigation
thin native shell
navigation in JS
thick native shell
only content in JS
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JavaScript Navigation
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JavaScript Navigation
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React Navigation
https:/
/reactnavigation.org/
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JavaScript Navigation
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React Navigation
https:/
/reactnavigation.org/
- reimplements iOS/Android behavior in pure JavaScript
- 3rd party library but officially recommended by RN team
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Native Navigation
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Native Navigation
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Wix React Native Navigation
https:/
/github.com/wix/react-native-navigation
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Native Navigation
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Wix React Native Navigation
https:/
/github.com/wix/react-native-navigation
Airbnb Native Navigation (Beta)
https:/
/github.com/airbnb/native-navigation
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ClassPass Native Navigation
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ClassPass Native Navigation
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ClassPass Native Navigation
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enum ReactRoute: String {
case findCity
case signUp
}
class ReactViewController {
init(route: Route, props: [String: Any])
}
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ClassPass Native Navigation
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enum ReactRoute: String {
case findCity
case signUp
}
class ReactViewController {
init(route: Route, props: [String: Any])
}
class FindCityViewController: ReactViewController {
init() { return super.init(route: .findCity) }
}
class SignUpViewController: ReactViewController {
init(city: City) {
return super.init(route: .signUp, props: [
"city_id": city.id,
]
}
}
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ClassPass Native Navigation
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render() {
const routes = {
'findCity': FindCity,
'signUp': SignUp,
}
const Component = routes[props.route]
return (
)
}
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ClassPass Native Navigation
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render() {
const routes = {
'findCity': FindCity,
'signUp': SignUp,
}
const Component = routes[props.route]
return (
)
}
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Sign up flow
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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React Native at ClassPass
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1
Venue detail
2
Sign up flow
3
Schedule list
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Schedule list
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Schedule list
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Schedule list
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Schedule list
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Schedule list
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Schedule list
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Schedule list
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Schedule list
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Should you use React Native
in your app?
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React Native at Airbnb
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React Native at Airbnb
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React Native at Airbnb
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React Native at Airbnb
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React Native at Airbnb
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React Native at Airbnb
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http://artsy.github.io/blog/2018/03/17/two-years-of-react-native/
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http://artsy.github.io/blog/2018/03/17/two-years-of-react-native/
https:/
/medium.com/@Pinterest_Engineering/
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“there were a number of technical and
organizational challenges that we were
unable to overcome that would have
made continuing to invest in React Native
a challenge”
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Sunsetting React Native at Airbnb
https://medium.com/airbnb-engineering/sunsetting-react-native-1868ba28e30a
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Technical challenges
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Technical challenges
- investing in infrastructure
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Technical challenges
- investing in infrastructure
- initial render time
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Technical challenges
- investing in infrastructure
- initial render time
- asynchronous native bridge
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https://www.youtube.com/watch?v=UcqRXTriUVI
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React Native's new architecture
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React Native's new architecture
- new architecture called Fabric
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React Native's new architecture
- new architecture called Fabric
- opt-in synchronous execution to help performance
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React Native's new architecture
- new architecture called Fabric
- opt-in synchronous execution to help performance
- JSI: shared memory between JS and native objects
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React Native's new architecture
- new architecture called Fabric
- opt-in synchronous execution to help performance
- JSI: shared memory between JS and native objects
https:/
/github.com/react-native-community/discussions-and-proposals/issues/40
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Organizational challenges
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Organizational challenges
- React Native is polarising
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Organizational challenges
- React Native is polarising
- React Native is still native
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Organizational challenges
- React Native is polarising
- React Native is still native
- hiring can be a challenge
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Should you use React Native in your app?
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Should you use React Native in your app?
- think about your inputs and outputs
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Should you use React Native in your app?
- think about your inputs and outputs
- think about your team and their skills
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Should you use React Native in your app?
- think about your inputs and outputs
- think about your team and their skills
- regularly re-evaluate
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Whats next?
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Thanks!
@neilkimmett
Speaker Hours:
Thursday @ 11am
Room 210