add options for measurements in settings view

Basic-Car-Maintenance/Shared/Localizable.xcstrings

@@ -1,6 +1,9 @@
 {
   "sourceLanguage" : "en",
   "strings" : {
+    "" : {
+
+    },
     "%@" : {
       "comment" : "Maintenance list item description 'Date' formatted",
       "localizations" : {
@@ -2719,6 +2722,9 @@
         }
       }
     },
+    "Imperial" : {
+      "comment" : "Imperial unit system"
+    },
     "It's open source and anyone can contribute to it." : {
       "comment" : "Tells the user they can contribute to the codebase.",
       "localizations" : {
@@ -3101,6 +3107,9 @@
         }
       }
     },
+    "Metric" : {
+      "comment" : "Metric unit system"
+    },
     "Mileage: %lld %@" : {
       "localizations" : {
         "en" : {
@@ -3853,6 +3862,9 @@
     },
     "Plate: %@" : {
 
+    },
+    "Preferred System" : {
+
     },
     "Preferred units" : {
       "comment" : "Label for units selected when adding an odometer reading",
@@ -5164,6 +5176,9 @@
         }
       }
     },
+    "Units" : {
+      "comment" : "Label to represent the options for measurement units"
+    },
     "Update" : {
       "comment" : "Label for submit button on form to update an existing entry",
       "localizations" : {

Basic-Car-Maintenance/Shared/Odometer/Views/AddOdometerReadingView.swift

@@ -13,13 +13,25 @@ struct AddOdometerReadingView: View {
     let vehicles: [Vehicle]
     let addTapped: (OdometerReading) -> Void
 
+    @AppStorage(AppStorageKeys.measurementSystem) 
+    private var defaultUnitSystem: MeasurementSystem = .default
+
     @Environment(\.dismiss) var dismiss
 
     @State private var date = Date()
     @State private var selectedVehicleID: String?
-    @State private var isMetric = false
+    @State private var isMetric: Bool
     @State private var distance = 0
 
+    init(
+        vehicles: [Vehicle],
+        addTapped: @escaping (OdometerReading) -> Void
+    ) {
+        self.vehicles = vehicles
+        self.addTapped = addTapped
+        self.isMetric = _defaultUnitSystem.wrappedValue == .metric
+    }
+
     var body: some View {
         NavigationStack {
             Form {
@@ -83,6 +95,9 @@ struct AddOdometerReadingView: View {
                     .disabled(distance < 0)
                 }
             }
+            .onChange(of: defaultUnitSystem) { _, newValue in
+                isMetric = newValue == .metric
+            }
         }
         .analyticsView("\(Self.self)")
     }

Basic-Car-Maintenance/Shared/Settings/Views/SettingsView.swift

@@ -11,6 +11,8 @@ import UniformTypeIdentifiers
 import TipKit
 
 struct SettingsView: View {
+    @AppStorage(AppStorageKeys.measurementSystem) private var defaultUnitSystem: MeasurementSystem = .default
+
     @Environment(ActionService.self) var actionService
     @Environment(\.scenePhase) var scenePhase
     @Environment(\.colorScheme) var colorScheme
@@ -88,6 +90,18 @@ struct SettingsView: View {
                     .foregroundStyle(.blue)
                 }
 
+                Section {
+                    Picker("Preferred System", selection: $defaultUnitSystem) { 
+                        ForEach(MeasurementSystem.allCases) { unit in
+                            Text(unit.title)
+                                .tag(unit)
+                        }
+                    }
+                    .foregroundStyle(.blue)
+                } header: {
+                    Text("Units", comment: "Label to represent the options for measurement units")
+                }
+
                 Section {
                     ForEach(viewModel.vehicles) { vehicle in
                         VStack(alignment: .leading, spacing: 2) {

Basic-Car-Maintenance/Shared/Utilities/AppStorageKeys.swift

@@ -0,0 +1,11 @@
+//
+//  AppStorageKeys.swift
+//  Basic-Car-Maintenance
+//
+//  https://github.com/mikaelacaron/Basic-Car-Maintenance
+//  See LICENSE for license information.
+//
+
+enum AppStorageKeys {
+    static let measurementSystem = "defaultMeasurementSystem"
+}

Basic-Car-Maintenance/Shared/Utilities/MeasurementSystem.swift

@@ -0,0 +1,35 @@
+//
+//  MeasurementSystem.swift
+//  Basic-Car-Maintenance
+//
+//  https://github.com/mikaelacaron/Basic-Car-Maintenance
+//  See LICENSE for license information.
+//
+
+import Foundation
+
+enum MeasurementSystem: String, Identifiable, CaseIterable {
+    case imperial
+    case metric
+
+    var id: UUID { UUID() }
+    var title: String {
+        switch self {
+        case .imperial:
+            return NSLocalizedString("Imperial", comment: "Imperial unit system")
+        case .metric:
+            return NSLocalizedString("Metric", comment: "Metric unit system")
+        }
+    }    
+
+    static var `default`: MeasurementSystem {
+        switch Locale.current.measurementSystem {
+        case .uk:
+            return .metric
+        case .us:
+            return .imperial
+        default:
+            return .metric
+        }
+    }
+}