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MVI in a nutshell
Aida Issayeva
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About me
Software Engineer
🤖 I build Android apps
Udacity Instructor
🐦 @aida_isay
🌐 cupsofcode.com
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Android Architecture
MVC MVP
MVVM MVI
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What is MVI?
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What is MVI?
Model View Intent
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Unidirectional flow! Or
reactive arch pattern
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https://proandroiddev.com/the-contract-of-the-model-view-intent-architecture-777f95706c1e
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Multiple User Actions
sealed class FeedIntent {
data class RestaurantClicked(val restaurantId: String) : FeedIntent()
data class LikeClicked(val restaurantId: String, val isLiked: Boolean) : FeedIntent()
}
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Multiple Results
val dataIntent = feedRestaurantsUseCase.execute()
.map {
FeedIntent.Data(restaurants = it.map { it.toUiModel(stringResources) })
}
.startWith(FeedIntent.Loading)
.onErrorReturn {
FeedIntent.Error(error = it)
}
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Single ViewState
data class FeedViewState(
val isLoading: Boolean = false,
val error: Throwable? = null,
val restaurants: List = emptyList(),
val toolbarTitle: String = "",
val searchedCity: String = "Hoboken",
val emptyListMessage: String = ""
)
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Reducer from multiple intents
into single viewstate.
__________________
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private val reducer =
BiFunction { previous, intent ->
when (intent) {
is FeedIntent.Data -> {
previous.copy(
restaurants = intent.restaurants,
isLoading = false,
toolbarTitle = "Sample",
emptyListMessage = ""
)
}
else -> previous
}
}
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UI subscription to
the single viewstate
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Benefits:
State Management Thread Safety Easy Testing
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Side effects:
Opportunity for
memory leaks
Boilerplate
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Checkout the
github project
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Thank you
@aida_isay cupsofcode.com
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Resources:
● Android MVI reactive architecture pattern
● Unidirectional state flow patterns
● Battle of the android architecture patterns