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// Combine MVVM https://github.com/V8tr/ModernMVVM
// https://github.com/V8tr/ModernMVVM/tree/master/ModernMVVM/Features/MovieDetails
import Foundation
import Combine
final class MovieDetailViewModel: ObservableObject {
@Published private(set) var state: State
private var bag = Set<AnyCancellable>()
private let input = PassthroughSubject<Event, Never>()
init(movieID: Int) {
state = .idle(movieID)
Publishers.system(
initial: state,
reduce: Self.reduce,
scheduler: RunLoop.main,
feedbacks: [
Self.whenLoading(),
Self.userInput(input: input.eraseToAnyPublisher())
]
)
.assign(to: \.state, on: self)
.store(in: &bag)
}
func send(event: Event) {
input.send(event)
}
}
// MARK: - Inner Types
extension MovieDetailViewModel {
enum State {
case idle(Int)
case loading(Int)
case loaded(MovieDetail)
case error(Error)
}
enum Event {
case onAppear
case onLoaded(MovieDetail)
case onFailedToLoad(Error)
}
struct MovieDetail {
let id: Int
let title: String
let overview: String?
let poster: URL?
let rating: Double?
let duration: String
let genres: [String]
let releasedAt: String
let language: String
init(movie: MovieDetailDTO) {
id = movie.id
title = movie.title
overview = movie.overview
poster = movie.poster
rating = movie.vote_average
let formatter = DateComponentsFormatter()
formatter.unitsStyle = .abbreviated
formatter.allowedUnits = [.minute, .hour]
duration = movie.runtime.flatMap { formatter.string(from: TimeInterval($0 * 60)) } ?? "N/A"
genres = movie.genres.map(\.name)
releasedAt = movie.release_date ?? "N/A"
language = movie.spoken_languages.first?.name ?? "N/A"
}
}
}
// MARK: - State Machine
extension MovieDetailViewModel {
static func reduce(_ state: State, _ event: Event) -> State {
switch state {
case .idle(let id):
switch event {
case .onAppear:
return .loading(id)
default:
return state
}
case .loading:
switch event {
case .onFailedToLoad(let error):
return .error(error)
case .onLoaded(let movie):
return .loaded(movie)
default:
return state
}
case .loaded:
return state
case .error:
return state
}
}
static func whenLoading() -> Feedback<State, Event> {
Feedback { (state: State) -> AnyPublisher<Event, Never> in
guard case .loading(let id) = state else { return Empty().eraseToAnyPublisher() }
return MoviesAPI.movieDetail(id: id)
.map(MovieDetail.init)
.map(Event.onLoaded)
.catch { Just(Event.onFailedToLoad($0)) }
.eraseToAnyPublisher()
}
}
static func userInput(input: AnyPublisher<Event, Never>) -> Feedback<State, Event> {
Feedback(run: { _ in
return input
})
}
} // filter() vs. compactMap()
// https://cocoacasts.com/collections/combine-essentials
private func setupBindings() {
reachablePublisher
.filter { $0 }
.sink { [weak self] _ in
self?.fetchEpisodes()
}.store(in: &subscriptions)
}
private func setupBindings() {
reachablePublisher
.compactMap { $0 ? $0 : nil }
.sink { [weak self] _ in
self?.fetchEpisodes()
}.store(in: &subscriptions)
} // AnyCancellable
var mySubscriber: AnyCancellable?
let mySinkSubscriber = remotePublisher
.sink { data in
print("received ", data)
}
mySubscriber = AnyCancellable(mySinkSubscriber)
// Alternatively
private var cancellableSet: Set<AnyCancellable> = []
let mySinkSubscriber = remotePublisher
.sink { data in
print("received ", data)
}
.store(in: &cancellableSet)// SwiftUI Published Binding
struct ReactiveForm: View {
@ObservedObject var model: ReactiveFormModel
// $model is a ObservedObject<ExampleModel>.Wrapper
// and $model.objectWillChange is a Binding<ObservableObjectPublisher>
@State private var buttonIsDisabled = true
// $buttonIsDisabled is a Binding<Bool>
var body: some View {
VStack {
Text("Reactive Form")
.font(.headline)
Form {
TextField("first entry", text: $model.firstEntry)
.textFieldStyle(RoundedBorderTextFieldStyle())
.lineLimit(1)
.multilineTextAlignment(.center)
.padding()
TextField("second entry", text: $model.secondEntry)
.textFieldStyle(RoundedBorderTextFieldStyle())
.multilineTextAlignment(.center)
.padding()
VStack {
ForEach(model.validationMessages, id: \.self) { msg in
Text(msg)
.foregroundColor(.red)
.font(.callout)
}
}
}
Button(action: {}) {
Text("Submit")
}.disabled(buttonIsDisabled)
.onReceive(model.submitAllowed) { submitAllowed in
self.buttonIsDisabled = !submitAllowed
}
.padding()
.background(RoundedRectangle(cornerRadius: 10) .stroke(Color.blue, lineWidth: 1)
)
Spacer()
}
}
}
struct HeadingView: View {
@ObservedObject var locationModel: LocationProxy
@State var lastHeading: CLHeading?
@State var lastLocation: CLLocation?
var body: some View {
VStack {
HStack {
Text("authorization status:")
Text(locationModel.authorizationStatusString())
}
if (locationModel.authorizationStatus == .notDetermined) {
Button(action: {
self.locationModel.requestAuthorization()
}) {
Image(systemName: "lock.shield")
Text("Request location authorization")
}
.padding()
.background(RoundedRectangle(cornerRadius: 10) .stroke(Color.blue, lineWidth: 1)
)
}
if (self.lastHeading != nil) {
Text("Heading: ")+Text(String(self.lastHeading!.description))
}
if (self.lastLocation != nil) {
Text("Location: ")+Text(lastLocation!.description)
ZStack {
Circle()
.stroke(Color.blue, lineWidth: 1)
GeometryReader { geometry in
Path { path in
let minWidthHeight = min(geometry.size.height, geometry.size.width)
path.move(to: CGPoint(x: geometry.size.width/2, y: geometry.size.height/2))
path.addLine(to: CGPoint(x: geometry.size.width/2, y: geometry.size.height/2 - minWidthHeight/2 + 5) )
}
.stroke()
.rotation(Angle(degrees: self.lastLocation!.course))
.animation(.linear)
}
}
}
}
.onReceive(self.locationModel.headingPublisher) { heading in
self.lastHeading = heading
}
.onReceive(self.locationModel.locationPublisher, perform: {
self.lastLocation = $0
})
}
}
struct ContentView : View {
@ObservedObject var model: ReactiveFormModel
var body: some View {
TabView {
ReactiveForm(model: model)
.tabItem {
Image(systemName: "1.circle")
Text("Reactive Form")
}
HeadingView(locationModel: LocationProxy())
.tabItem {
Image(systemName: "mappin.circle")
Text("Location")
}
}
}
}// https://heckj.github.io/swiftui-notes/#reference-swiftui
// SwiftUI Binding
class Contact : ObservableObject {
@Published var name: String
@Published var age: Int
init(name: String, age: Int) {
self.name = name
self.age = age
}
func haveBirthday() -> Int {
age += 1
return age
}
}
let john = Contact(name: "John Appleseed", age: 24)
let cancellable = john.objectWillChange.sink { _ in
expectation.fulfill()
print("will change")
// Prints "will change"
// Prints "25"
}
print(john.haveBirthday())