118 lines
3.2 KiB
Swift
118 lines
3.2 KiB
Swift
//
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// Model.swift
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// Meta
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//
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// Created by david-swift on 19.07.2024.
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//
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import Foundation
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/// A model is a special type of state which can be updated from within itself.
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/// This is useful for complex asynchronous operations such as networking.
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///
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/// Use the model protocol in the following way:
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/// ```swift
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/// struct TestView: View {
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///
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/// @State private var test = TestModel()
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///
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/// var view: Body {
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/// Button(test.test) {
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/// test.updateAsync()
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/// // You can also update via
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/// // test.test = "hello"
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/// // as with any state values
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/// }
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/// }
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///
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/// }
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///
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/// struct TestModel: Model {
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///
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/// var test = "Label"
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///
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/// var model: ModelData? // Use exactly this line in every model
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///
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/// func updateAsync() {
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/// Task {
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/// // Do something asynchronously
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/// // Remember to execute the following line in the correct context, depending on the backend
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/// // As an example, you might have to run it on the main thread in some cases
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/// setModel { $0.test = "\(Int.random(in: 1...10))" }
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/// }
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/// }
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///
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/// }
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///
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/// ```
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public protocol Model {
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/// Data about the model's state value.
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var model: ModelData? { get set }
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/// Set the model up.
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///
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/// At the point this function gets called, the model data is available.
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/// Therefore, you can use it for initializing callbacks of children.
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mutating func setup()
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}
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/// Data about a model's state value.
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public struct ModelData {
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/// The state value's identifier.
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var id: UUID
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/// Whether to force update the views when this value changes.
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var force: Bool
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}
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extension Model {
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/// Get the value as a binding using the `$` prefix.
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public var binding: Binding<Self> {
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.init {
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getModel()
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} set: { newValue in
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guard let data = model else {
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return
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}
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StateManager.setState(id: data.id, value: newValue)
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StateManager.updateState(id: data.id)
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StateManager.updateViews(force: data.force)
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}
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}
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/// Set the model up.
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///
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/// At the point this function gets called, the model data is available.
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/// Therefore, you can use it for initializing callbacks of children.
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mutating func setup() { }
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/// Update the model.
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/// - Parameter setModel: Update the model in this closure.
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public func setModel(_ setModel: (inout Self) -> Void) {
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guard let data = model else {
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return
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}
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var model = getModel()
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setModel(&model)
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StateManager.setState(id: data.id, value: model)
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StateManager.updateState(id: data.id)
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StateManager.updateViews(force: data.force)
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}
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/// Get the current version of the model.
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/// - Returns: The model.
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///
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/// This is only useful when calling from a context where the model itself is outdated.
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/// Otherwise, directly call the properties.
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public func getModel() -> Self {
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guard let data = model else {
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return self
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}
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return StateManager.getState(id: data.id) as? Self ?? self
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}
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}
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