Add new option set picker

Sources/SpeziViews/Resources/Localizable.xcstrings

@@ -1,6 +1,12 @@
 {
   "sourceLanguage" : "en",
   "strings" : {
+    "" : {
+
+    },
+    "%lld selected" : {
+
+    },
     "A" : {
 
     },
@@ -28,6 +34,9 @@
     },
     "Dismiss" : {
 
+    },
+    "Empty" : {
+
     },
     "Error" : {
       "comment" : "View State default error title",
@@ -96,6 +105,15 @@
     },
     "None" : {
 
+    },
+    "nothing selected" : {
+
+    },
+    "Option %u" : {
+
+    },
+    "Test" : {
+
     }
   },
   "version" : "1.0"

Sources/SpeziViews/Views/Controls/OptionSetPicker.swift

@@ -0,0 +1,225 @@
+//
+// This source file is part of the Spezi open-source project
+//
+// SPDX-FileCopyrightText: 2025 Stanford University and the project authors (see CONTRIBUTORS.md)
+//
+// SPDX-License-Identifier: MIT
+//
+
+import SwiftUI
+
+/// The view style for an `OptionSetPicker`.
+public enum OptionSetPickerStyle {
+    /// The picker is rendered inline (e.g., in a List view).
+    case inline
+    /// The picker is rendered as a menu.
+    case menu
+}
+
+
+@available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *)
+private struct ViewBasedOnVisibility<Unlabeled: View, Labeled: View>: View {
+    private let unlabeled: Unlabeled
+    private let labeled: Labeled
+
+    @Environment(\.labelsVisibility)
+    private var labelsVisibility
+
+
+    var body: some View {
+        switch labelsVisibility {
+        case .hidden:
+            unlabeled
+        case .automatic, .visible:
+            labeled
+        }
+    }
+
+    init(@ViewBuilder unlabeled: () -> Unlabeled, @ViewBuilder labeled: () -> Labeled) {
+        self.unlabeled = unlabeled()
+        self.labeled = labeled()
+    }
+}
+
+
+/// Create a picker based on a `OptionSet` selection.
+///
+/// If you have a type that both conforms to [`OptionSet`](https://developer.apple.com/documentation/swift/optionset)  and
+/// ``PickerValue`` you can use this Picker for your `selection` value.
+///
+/// - Note: `OptionSet` by definition allows the selection of multiple values. Therefore, `OptionSetPicker` is always implemented as an
+///     inline Picker (e.g., as part of a List view) and allows to selection one or more entries.
+///
+/// - Note: Displaying labels is only supported on iOS 18 and newer.
+public struct OptionSetPicker<Label: View, Value: OptionSet & PickerValue>: View
+    where Value.AllCases: RandomAccessCollection, Value == Value.Element {
+    private let allowEmptySelection: Bool
+    private let style: OptionSetPickerStyle
+
+    private let label: Label
+
+    @Binding private var selection: Value
+
+    private var selectionCount: Int {
+        Value.allCases.count { value in
+            selection.contains(value)
+        }
+    }
+
+    private var singleSelection: Value? {
+        Value.allCases.first { value in
+            selection.contains(value)
+        }
+    }
+
+    public var body: some View {
+        switch style {
+        case .inline:
+            let view = ForEach(Value.allCases, id: \.self) { value in
+                button(for: value)
+            }
+
+            if #available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *) {
+                ViewBasedOnVisibility {
+                    view
+                } labeled: {
+                    Section {
+                        view
+                    } header: {
+                        label
+                    }
+                }
+            } else {
+                view
+            }
+        case .menu:
+            Menu {
+                ForEach(Value.allCases, id: \.self) { value in
+                    button(for: value)
+                }
+            } label: {
+                LabeledContent {
+                    HStack {
+                        if selectionCount < 2 {
+                            if let value = singleSelection {
+                                Text(value.localizedStringResource)
+                            } else {
+                                Text("nothing selected")
+                                    .italic()
+                            }
+                        } else {
+                            Text("\(selectionCount) selected")
+                        }
+                        Image(systemName: "chevron.up.chevron.down")
+                            .accessibilityHidden(true)
+                            .font(.footnote)
+                            .fontWeight(.medium)
+                    }
+                } label: {
+                    if #available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *) {
+                        ViewBasedOnVisibility {
+                            EmptyView()
+                        } labeled: {
+                            label
+                                .foregroundStyle(Color.primary)
+                        }
+                    } else {
+                        label
+                            .foregroundStyle(Color.primary)
+                    }
+                }
+            }
+                .menuActionDismissBehavior(.disabled) // disable for multi selection
+        }
+    }
+
+
+    /// Create a new picker for your selection.
+    /// - Parameters:
+    ///   - selection: The `OptionSet`-based selection.
+    ///   - style: The style how the picker is displayed.
+    ///   - allowEmptySelection: Flag indicating if an empty selection is allowed.
+    ///   - label: The label view.
+    public init(selection: Binding<Value>, style: OptionSetPickerStyle = .menu, allowEmptySelection: Bool = false, @ViewBuilder label: () -> Label) {
+        self.style = style
+        self.allowEmptySelection = allowEmptySelection
+        self.label = label()
+        self._selection = selection
+    }
+
+    /// Create a new picker for your selection.
+    /// - Parameters:
+    ///   - titleKey: The localized label.
+    ///   - selection: The `OptionSet`-based selection.
+    ///   - style: The style how the picker is displayed.
+    ///   - allowEmptySelection: Flag indicating if an empty selection is allowed.
+    public init(
+        _ titleKey: LocalizedStringResource,
+        selection: Binding<Value>,
+        style: OptionSetPickerStyle = .menu,
+        allowEmptySelection: Bool = false
+    ) where Label == Text {
+        self.init(selection: selection, style: style, allowEmptySelection: allowEmptySelection) {
+            Text(titleKey)
+        }
+    }
+
+    @ViewBuilder
+    private func button(for value: Value) -> some View {
+        Button {
+            if selection.contains(value) {
+                if selection != value || allowEmptySelection {
+                    selection.remove(value)
+                }
+            } else {
+                selection.insert(value)
+            }
+        } label: {
+            HStack {
+                Text(value.localizedStringResource)
+                    .tint(.primary)
+                Spacer()
+                if selection.contains(value) {
+                    Image(systemName: "checkmark")
+                        .foregroundStyle(Color.accentColor)
+                        .fontWeight(.semibold)
+                        .accessibilityHidden(true)
+                }
+            }
+        }
+    }
+}
+
+
+#if DEBUG
+extension PreviewLayout {
+    fileprivate struct Options: OptionSet, PickerValue {
+        var rawValue: UInt8
+
+        static let option1 = Options(rawValue: 1 << 0)
+        static let option2 = Options(rawValue: 1 << 1)
+
+        static let allCases: [Options] = [.option1, .option2]
+
+        init(rawValue: UInt8) {
+            self.rawValue = rawValue
+        }
+
+        var localizedStringResource: LocalizedStringResource {
+            "Option \(rawValue)"
+        }
+    }
+}
+
+#Preview {
+    @Previewable @State var selection: PreviewLayout.Options = []
+    @Previewable @State var picker: String = ""
+
+    List {
+        OptionSetPicker("Test", selection: $selection)
+        Picker("Test", selection: $picker) {
+            Text("Empty").tag("")
+        }
+    }
+}
+#endif