103 lines
4.6 KiB
Swift
103 lines
4.6 KiB
Swift
#if compiler(>=5.5)
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extension View {
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/// Presents an alert from a binding to optional alert state.
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///
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/// SwiftUI's `alert` view modifiers are driven by two disconnected pieces of state: an
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/// `isPresented` binding to a boolean that determines if the alert should be presented, and
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/// optional alert `data` that is used to customize its actions and message.
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///
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/// Modeling the domain in this way unfortunately introduces a couple invalid runtime states:
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///
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/// * `isPresented` can be `true`, but `data` can be `nil`.
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/// * `isPresented` can be `false`, but `data` can be non-`nil`.
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///
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/// On top of that, SwiftUI's `alert` modifiers take static titles, which means the title cannot
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/// be dynamically computed from the alert data.
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///
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/// This overload addresses these shortcomings with a streamlined API. First, it eliminates the
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/// invalid runtime states at compile time by driving the alert's presentation from a single,
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/// optional binding. When this binding is non-`nil`, the alert will be presented. Further, the
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/// title can be customized from the alert data.
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///
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/// ```swift
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/// struct AlertDemo: View {
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/// @State var randomMovie: Movie?
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///
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/// var body: some View {
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/// Button("Pick a random movie", action: self.getRandomMovie)
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/// .alert(
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/// title: { Text($0.title) },
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/// unwrapping: self.$randomMovie,
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/// actions: { _ in
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/// Button("Pick another", action: self.getRandomMovie)
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/// },
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/// message: { Text($0.summary) }
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/// )
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/// }
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///
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/// func getRandomMovie() {
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/// self.randomMovie = Movie.allCases.randomElement()
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/// }
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/// }
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/// ```
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///
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/// - Parameters:
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/// - title: A closure returning the alert's title given the current alert state.
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/// - value: A binding to an optional value that determines whether an alert should be
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/// presented. When the binding is updated with non-`nil` value, it is unwrapped and passed
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/// to the modifier's closures. You can use this data to populate the fields of an alert
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/// that the system displays to the user. When the user presses or taps one of the alert's
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/// actions, the system sets this value to `nil` and dismisses the alert.
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/// - actions: A view builder returning the alert's actions given the current alert state.
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/// - message: A view builder returning the message for the alert given the current alert
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/// state.
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@available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
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public func alert<Value, A: View, M: View>(
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title: (Value) -> Text,
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unwrapping value: Binding<Value?>,
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@ViewBuilder actions: (Value) -> A,
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@ViewBuilder message: (Value) -> M
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) -> some View {
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self.alert(
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value.wrappedValue.map(title) ?? Text(""),
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isPresented: value.isPresent(),
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presenting: value.wrappedValue,
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actions: actions,
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message: message
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)
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}
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/// Presents an alert from a binding to an optional enum, and a case path to a specific case.
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///
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/// A version of `alert(unwrapping:)` that works with enum state.
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///
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/// - Parameters:
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/// - title: A closure returning the alert's title given the current alert state.
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/// - enum: A binding to an optional enum that holds alert state at a particular case. When
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/// the binding is updated with a non-`nil` enum, the case path will attempt to extract this
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/// state
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/// and then pass it to the modifier's closures. You can use it to populate the fields of an
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/// alert that the system displays to the user. When the user presses or taps one of the
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/// alert's actions, the system sets this value to `nil` and dismisses the alert.
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/// - casePath: A case path that identifies a particular case that holds alert state.
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/// - actions: A view builder returning the alert's actions given the current alert state.
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/// - message: A view builder returning the message for the alert given the current alert
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/// state.
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@available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
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public func alert<Enum, Case, A: View, M: View>(
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title: (Case) -> Text,
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unwrapping enum: Binding<Enum?>,
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case casePath: CasePath<Enum, Case>,
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@ViewBuilder actions: (Case) -> A,
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@ViewBuilder message: (Case) -> M
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) -> some View {
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self.alert(
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title: title,
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unwrapping: `enum`.case(casePath),
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actions: actions,
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message: message
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)
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}
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}
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#endif
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