Address some PR comments

Author: bbrk24

Examples/Sources/DatePickerExample/DatePickerApp.swift

@@ -12,40 +12,25 @@ struct DatePickerApp: App {
     @State var date = Date()
     @State var style: DatePickerStyle? = .automatic
 
-    var allStyles: [DatePickerStyle]
-
-    init() {
-        allStyles = [.automatic]
-
-        if #available(iOS 14, macCatalyst 14, *) {
-            allStyles.append(.graphical)
-        }
-
-        #if !canImport(GtkBackend)
-            if #available(iOS 13.4, macCatalyst 13.4, *) {
-                allStyles.append(.compact)
-                #if os(iOS) || os(visionOS) || canImport(WinUIBackend)
-                    allStyles.append(.wheel)
-                #endif
-            }
-        #endif
-    }
+    @Environment(\.supportedDatePickerStyles) var allStyles: [DatePickerStyle]
 
     var body: some Scene {
         WindowGroup("Date Picker") {
-            VStack {
-                Text("Selected date: \(date)")
+            #hotReloadable {
+                VStack {
+                    Text("Selected date: \(date)")
 
-                Picker(of: allStyles, selection: $style)
+                    Picker(of: allStyles, selection: $style)
 
-                DatePicker(
-                    "Test Picker",
-                    selection: $date
-                )
-                .datePickerStyle(style ?? .automatic)
+                    DatePicker(
+                        "Test Picker",
+                        selection: $date
+                    )
+                    .datePickerStyle(style ?? .automatic)
 
-                Button("Reset date") {
-                    date = Date()
+                    Button("Reset date to now") {
+                        date = Date()
+                    }
                 }
             }
         }

Sources/AppKitBackend/AppKitBackend.swift

@@ -25,6 +25,7 @@ public final class AppKitBackend: AppBackend {
     public let menuImplementationStyle = MenuImplementationStyle.dynamicPopover
     public let canRevealFiles = true
     public let deviceClass = DeviceClass.desktop
+    public let supportedDatePickerStyles: [DatePickerStyle] = [.automatic, .graphical, .compact]
 
     public var scrollBarWidth: Int {
         // We assume that all scrollers have their controlSize set to `.regular` by default.
@@ -1708,7 +1709,7 @@ public final class AppKitBackend: AppBackend {
     // choice for the current calendar means the cursor position is reset after every keystroke. I
     // know of no simple way to tell whether NSDatePicker requires or forbids eras for a given
     // calendar, so in lieu of that I have hardcoded the calendar identifiers.
-    private let calendarsWithEras: Set<Calendar.Identifier> = [
+    private let calendarsRequiringEra: Set<Calendar.Identifier> = [
         .buddhist, .coptic, .ethiopicAmeteAlem, .ethiopicAmeteMihret, .indian, .islamic,
         .islamicCivil, .islamicTabular, .islamicUmmAlQura, .japanese, .persian, .republicOfChina,
     ]
@@ -1744,7 +1745,7 @@ public final class AppKitBackend: AppBackend {
         var elementFlags: NSDatePicker.ElementFlags = []
         if components.contains(.date) {
             elementFlags.insert(.yearMonthDay)
-            if calendarsWithEras.contains(environment.calendar.identifier) {
+            if calendarsRequiringEra.contains(environment.calendar.identifier) {
                 elementFlags.insert(.era)
             }
         }

Sources/Gtk/Utility/GDateTime.swift

@@ -13,7 +13,7 @@ public class GDateTime {
         self.pointer = pointer
     }
 
-    public convenience init?(unixEpoch: TimeInterval) {
+    public convenience init?(unixEpoch: Int) {
         // g_date_time_new_from_unix_utc_usec appears to be too new
         self.init(g_date_time_new_from_unix_utc(gint64(unixEpoch)))
     }
@@ -41,7 +41,7 @@ public class GDateTime {
     }
 
     public convenience init!(_ date: Date) {
-        self.init(unixEpoch: date.timeIntervalSince1970)
+        self.init(unixEpoch: Int(date.timeIntervalSince1970))
     }
 
     deinit {

Sources/Gtk3Backend/Gtk3Backend.swift

@@ -37,6 +37,7 @@ public final class Gtk3Backend: AppBackend {
     public let menuImplementationStyle = MenuImplementationStyle.dynamicPopover
     public let canRevealFiles = true
     public let deviceClass = DeviceClass.desktop
+    public let supportedDatePickerStyles: [DatePickerStyle] = []
 
     var gtkApp: Application
 

Sources/GtkBackend/GtkBackend.swift

@@ -36,6 +36,7 @@ public final class GtkBackend: AppBackend {
     public let menuImplementationStyle = MenuImplementationStyle.dynamicPopover
     public let canRevealFiles = true
     public let deviceClass = DeviceClass.desktop
+    public let supportedDatePickerStyles: [DatePickerStyle] = [.automatic, .graphical]
 
     var gtkApp: Application
 
@@ -1517,9 +1518,6 @@ public final class GtkBackend: AppBackend {
         if components.contains(.hourAndMinute) {
             print("Warning: time picker is unimplemented on GtkBackend")
         }
-        if environment.datePickerStyle != .automatic && environment.datePickerStyle != .graphical {
-            print("Warning: only DatePickerStyle.graphical is implemented in GtkBackend")
-        }
 
         let calendarWidget = datePicker as! Gtk.Calendar
         calendarWidget.date = date
@@ -1661,7 +1659,7 @@ final class TimePicker: Box {
             case .zeroToEleven, .zeroToTwentyThree: 0
             case .oneToTwelve, .oneToTwentyFour: 1
             #if os(macOS)
-                @unknown default: fatalError()
+                @unknown default: fatalError("Unrecognized hourCycle \(hourCycle)")
             #endif
         }
     }
@@ -1673,7 +1671,7 @@ final class TimePicker: Box {
             case .zeroToTwentyThree: 23
             case .oneToTwentyFour: 24
             #if os(macOS)
-                @unknown default: fatalError()
+                @unknown default: fatalError("Unrecognized hourCycle \(hourCycle)")
             #endif
         }
     }
@@ -1773,7 +1771,7 @@ final class TimePicker: Box {
             case .zeroToTwentyThree: value % 24
             case .oneToTwentyFour: (value + 23) % 24 + 1
             #if os(macOS)
-                @unknown default: fatalError()
+                @unknown default: fatalError("Unrecognized hourCycle \(hourCycle)")
             #endif
         }
     }

Sources/SwiftCrossUI/Backend/AppBackend.swift

@@ -97,6 +97,10 @@ public protocol AppBackend: Sendable {
     /// Mobile backends generally can't.
     var canRevealFiles: Bool { get }
 
+    /// The supported date picker styles. Must include ``DatePickerStyle/automatic`` if date pickers
+    /// are supported at all.
+    nonisolated var supportedDatePickerStyles: [DatePickerStyle] { get }
+
     /// Often in UI frameworks (such as Gtk), code is run in a callback
     /// after starting the app, and hence this generic root window creation
     /// API must reflect that. This is always the first method to be called

Sources/SwiftCrossUI/Environment/EnvironmentValues.swift

@@ -196,9 +196,11 @@ public struct EnvironmentValues {
     /// The current time zone that views should use when handling dates.
     public var timeZone: TimeZone
 
-    #if !os(tvOS)
-        public var datePickerStyle: DatePickerStyle
-    #endif
+    /// The display style used by ``DatePicker``.
+    public var datePickerStyle: DatePickerStyle
+
+    /// The display styles supported by ``DatePicker``. ``datePickerStyle`` must be one of these.
+    public let supportedDatePickerStyles: [DatePickerStyle]
 
     /// Creates the default environment.
     init<Backend: AppBackend>(backend: Backend) {
@@ -224,9 +226,8 @@ public struct EnvironmentValues {
         isTextSelectionEnabled = false
         calendar = .autoupdatingCurrent
         timeZone = .autoupdatingCurrent
-        #if !os(tvOS)
-            datePickerStyle = .automatic
-        #endif
+        datePickerStyle = .automatic
+        supportedDatePickerStyles = backend.supportedDatePickerStyles
     }
 
     /// Returns a copy of the environment with the specified property set to the

Sources/SwiftCrossUI/Views/DatePicker.swift

@@ -12,6 +12,18 @@ public struct DatePickerComponents: OptionSet, Sendable {
         self.rawValue = 0
     }
 
+    /*
+     * These magic numbers are the same as SwiftUI. It's actually a bitfield:
+     *
+     *                        smhdMy--
+     *                   date 00011100
+     *          hourAndMinute 01100000
+     *    hourMinuteAndSecond 11100000
+     *
+     * Like SwiftUI, not all combinations are valid (SwiftUI fatalErrors if you try to get creative
+     * with your choice of flags), and hourMinuteAndSecond intentionally includes hourAndMinute.
+     */
+
     public static let date = DatePickerComponents(rawValue: 0x1C)
     public static let hourAndMinute = DatePickerComponents(rawValue: 0x60)
 
@@ -21,7 +33,6 @@ public struct DatePickerComponents: OptionSet, Sendable {
     public static let hourMinuteAndSecond = DatePickerComponents(rawValue: 0xE0)
 }
 
-@available(tvOS, unavailable)
 public enum DatePickerStyle: Sendable, Hashable {
     /// A date input chosen by the backend.
     case automatic
@@ -58,7 +69,7 @@ public struct DatePicker<Label: View> {
     ///   - label: The view to be shown next to the date input.
     public nonisolated init(
         selection: Binding<Date>,
-        range: ClosedRange<Date> = Date.distantPast...Date.distantFuture,
+        in range: ClosedRange<Date> = Date.distantPast...Date.distantFuture,
         displayedComponents: DatePickerComponents = [.hourAndMinute, .date],
         @ViewBuilder label: () -> Label
     ) {
@@ -79,7 +90,7 @@ public struct DatePicker<Label: View> {
     public nonisolated init(
         _ label: String,
         selection: Binding<Date>,
-        range: ClosedRange<Date> = Date.distantPast...Date.distantFuture,
+        in range: ClosedRange<Date> = Date.distantPast...Date.distantFuture,
         displayedComponents: DatePickerComponents = [.hourAndMinute, .date]
     ) where Label == Text {
         self.label = Text(label)

Sources/SwiftCrossUI/Views/Modifiers/DatePickerStyleModifier.swift

@@ -1,13 +1,12 @@
 extension View {
-    @available(tvOS, unavailable)
     public func datePickerStyle(_ style: DatePickerStyle) -> some View {
-        #if os(tvOS)
-            assertionFailure()
-            return EmptyView()
-        #else
-            EnvironmentModifier(self) { environment in
-                environment.with(\.datePickerStyle, style)
+        EnvironmentModifier(self) { environment in
+            var style = style
+            if !environment.supportedDatePickerStyles.contains(style) {
+                assertionFailure("Unsupported date picker style: \(style)")
+                style = .automatic
             }
-        #endif
+            return environment.with(\.datePickerStyle, style)
+        }
     }
 }

Sources/UIKitBackend/UIKitBackend.swift

@@ -44,6 +44,20 @@ public final class UIKitBackend: AppBackend {
         }
     }
 
+    public nonisolated var supportedDatePickerStyles: [DatePickerStyle] {
+        #if os(tvOS)
+            []
+        #else
+            if #available(iOS 14, macCatalyst 14, *) {
+                [.automatic, .graphical, .compact, .wheel]
+            } else if #available(iOS 13.4, macCatalyst 13.4, *) {
+                [.automatic, .compact, .wheel]
+            } else {
+                [.automatic]
+            }
+        #endif
+    }
+
     var onTraitCollectionChange: (() -> Void)?
 
     private let appDelegateClass: ApplicationDelegate.Type