ios: dark/light mode toggle (#975)

apps/ios/Shared/Views/UserSettings/AppearanceSettings.swift

@@ -10,10 +10,15 @@ import SwiftUI
 
 let defaultAccentColor = CGColor.init(red: 0, green: 0.533, blue: 1, alpha: 1)
 
+let interfaceStyles: [UIUserInterfaceStyle] = [.unspecified, .light, .dark]
+
+let interfaceStyleNames: [LocalizedStringKey] = ["System", "Light", "Dark"]
+
 struct AppearanceSettings: View {
     @EnvironmentObject var sceneDelegate: SceneDelegate
     @State private var iconLightTapped = false
     @State private var iconDarkTapped = false
+    @State private var userInterfaceStyle = getUserInterfaceStyleDefault()
     @State private var uiTintColor = getUIAccentColorDefault()
 
     var body: some View {
@@ -28,6 +33,11 @@ struct AppearanceSettings: View {
                 }
 
                 Section {
+                    Picker("Theme", selection: $userInterfaceStyle) {
+                        ForEach(interfaceStyles, id: \.self) { style in
+                            Text(interfaceStyleNames[interfaceStyles.firstIndex(of: style) ?? 0])
+                        }
+                    }
                     ColorPicker("Accent color", selection: $uiTintColor, supportsOpacity: false)
                 } header: {
                     Text("Colors")
@@ -39,6 +49,10 @@ struct AppearanceSettings: View {
                         Text("Reset colors").font(.callout)
                     }
                 }
+                .onChange(of: userInterfaceStyle) { _ in
+                    sceneDelegate.window?.overrideUserInterfaceStyle = userInterfaceStyle
+                    setUserInterfaceStyleDefault(userInterfaceStyle)
+                }
                 .onChange(of: uiTintColor) { _ in
                     sceneDelegate.window?.tintColor = UIColor(cgColor: uiTintColor)
                     setUIAccentColorDefault(uiTintColor)
@@ -84,6 +98,25 @@ func setUIAccentColorDefault(_ color: CGColor) {
     }
 }
 
+func getUserInterfaceStyleDefault() -> UIUserInterfaceStyle {
+    switch UserDefaults.standard.integer(forKey: DEFAULT_USER_INTERFACE_STYLE) {
+    case 1: return .light
+    case 2: return .dark
+    default: return .unspecified
+    }
+}
+
+func setUserInterfaceStyleDefault(_ style: UIUserInterfaceStyle) {
+    var v: Int
+    switch style {
+    case .unspecified: v = 0
+    case .light: v = 1
+    case .dark: v = 2
+    default: v = 0
+    }
+    UserDefaults.standard.set(v, forKey: DEFAULT_USER_INTERFACE_STYLE)
+}
+
 struct AppearanceSettings_Previews: PreviewProvider {
     static var previews: some View {
         AppearanceSettings()

apps/ios/Shared/Views/UserSettings/SettingsView.swift

@@ -29,6 +29,7 @@ let DEFAULT_DEVELOPER_TOOLS = "developerTools"
 let DEFAULT_ACCENT_COLOR_RED = "accentColorRed"
 let DEFAULT_ACCENT_COLOR_GREEN = "accentColorGreen"
 let DEFAULT_ACCENT_COLOR_BLUE = "accentColorBlue"
+let DEFAULT_USER_INTERFACE_STYLE = "userInterfaceStyle"
 
 let appDefaults: [String: Any] = [
     DEFAULT_SHOW_LA_NOTICE: false,
@@ -42,7 +43,8 @@ let appDefaults: [String: Any] = [
     DEFAULT_DEVELOPER_TOOLS: false,
     DEFAULT_ACCENT_COLOR_RED: 0.000,
     DEFAULT_ACCENT_COLOR_GREEN: 0.533,
-    DEFAULT_ACCENT_COLOR_BLUE: 1.000
+    DEFAULT_ACCENT_COLOR_BLUE: 1.000,
+    DEFAULT_USER_INTERFACE_STYLE: 0
 ]
 
 private var indent: CGFloat = 36