9f847454e7
* Fix Timeline on Xcode 14/iOS 16
Raise requirement to iOS 16+
Reduce pagination jumping.
Sonarcloud fixes.
Fix verification test.
Adopt if let optional { syntax.
* Remove unused ScrollViewReader
The ScrollViewReader didn't appear to change the behaviour.
* Fix warnings on Run Scripts.
Run script build phase 'SwiftLint' will be run during every build because it does not specify any outputs. To address this warning, either add output dependencies to the script phase, or configure it to run in every build by unchecking "Based on dependency analysis" in the script phase.
113 lines
4.1 KiB
Swift
113 lines
4.1 KiB
Swift
//
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// Copyright 2022 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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import Combine
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import Foundation
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/// A constrained and concise interface for interacting with the ViewModel.
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///
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/// This class is closely bound to`StateStoreViewModel`. It provides the exact interface the view should need to interact
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/// ViewModel (as modelled on our previous template architecture with the addition of two-way binding):
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/// - The ability read/observe view state
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/// - The ability to send view events
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/// - The ability to bind state to a specific portion of the view state safely.
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/// This class was brought about a little bit by necessity. The most idiomatic way of interacting with SwiftUI is via `@Published`
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/// properties which which are property wrappers and therefore can't be defined within protocols.
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/// A similar approach is taken in libraries like [CombineFeedback](https://github.com/sergdort/CombineFeedback).
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/// It provides a nice layer of consistency and also safety. As we are not passing the `ViewModel` to the view directly, shortcuts/hacks
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/// can't be made into the `ViewModel`.
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@dynamicMemberLookup
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@MainActor
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class ViewModelContext<ViewState: BindableState, ViewAction>: ObservableObject {
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// MARK: - Properties
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// MARK: Private
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fileprivate let viewActions: PassthroughSubject<ViewAction, Never>
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// MARK: Public
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/// Get-able/Observable `Published` property for the `ViewState`
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@Published fileprivate(set) var viewState: ViewState
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/// Set-able/Bindable access to the bindable state.
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subscript<T>(dynamicMember keyPath: WritableKeyPath<ViewState.BindStateType, T>) -> T {
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get { viewState.bindings[keyPath: keyPath] }
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set { viewState.bindings[keyPath: keyPath] = newValue }
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}
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// MARK: Setup
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init(initialViewState: ViewState) {
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self.viewActions = PassthroughSubject()
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self.viewState = initialViewState
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}
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// MARK: Public
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/// Send a `ViewAction` to the `ViewModel` for processing.
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/// - Parameter viewAction: The `ViewAction` to send to the `ViewModel`.
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func send(viewAction: ViewAction) {
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viewActions.send(viewAction)
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}
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}
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/// A common ViewModel implementation for handling of `State` and `ViewAction`s
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///
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/// Generic type State is constrained to the BindableState protocol in that it may contain (but doesn't have to)
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/// a specific portion of state that can be safely bound to.
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/// If we decide to add more features to our state management (like doing state processing off the main thread)
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/// we can do it in this centralised place.
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@MainActor
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class StateStoreViewModel<State: BindableState, ViewAction> {
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typealias Context = ViewModelContext<State, ViewAction>
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// MARK: - Properties
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// MARK: Public
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/// For storing subscription references.
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///
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/// Left as public for `ViewModel` implementations convenience.
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var cancellables = Set<AnyCancellable>()
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/// Constrained interface for passing to Views.
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var context: Context
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var state: State {
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get { context.viewState }
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set { context.viewState = newValue }
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}
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// MARK: Setup
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init(initialViewState: State) {
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context = Context(initialViewState: initialViewState)
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context.viewActions.sink { [weak self] action in
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guard let self else { return }
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Task { await self.process(viewAction: action) }
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}
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.store(in: &cancellables)
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}
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/// Override to handles incoming `ViewAction`s from the `ViewModel`.
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/// - Parameter viewAction: The `ViewAction` to be processed in `ViewModel` implementation.
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func process(viewAction: ViewAction) async {
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// Default implementation, -no-op
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}
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}
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