Give each Monero account a swipeable card with its balance and QR

apps/ios/Koins/AppModel.swift

@@ -15,7 +15,7 @@ final class AppModel: ObservableObject {
   @Published var moneroReady = false
   @Published var moneroAddress: String?
   @Published var moneroAccounts: [MoneroAccount] = []
-  @Published var prices = PriceService.Prices()
+  @Published var prices = PriceService.Prices(currency: "USD")
 
   /// Whether the app is behind the biometric lock screen right now.
   @Published var locked = false
@@ -57,24 +57,38 @@ final class AppModel: ObservableObject {
 
   // MARK: - Fiat display
 
-  private static let fiatFormatter: NumberFormatter = {
+  /// The fiat currency the wallet shows; persisted, and changing it refetches
+  /// the price cache.
+  var fiatCurrency: String {
+    get { UserDefaults.standard.string(forKey: "koins.fiatCurrency") ?? "USD" }
+    set {
+      UserDefaults.standard.set(newValue, forKey: "koins.fiatCurrency")
+      objectWillChange.send()
+      Task { await refreshPrices() }
+    }
+  }
+
+  /// The current chain's balance in the chosen fiat currency, when a price is
+  /// known.
+  var fiatBalance: String? {
+    fiatValue(of: balance.total, chain: chain)
+  }
+
+  /// Converts a chain amount into the chosen fiat currency, when a price is
+  /// known.
+  func fiatValue(of amount: String, chain: Chain) -> String? {
+    let price = chain == .xrp ? prices.xrp : prices.xmr
+    guard let price, let value = Decimal(string: amount) else { return nil }
+    let fiat = value * Decimal(price)
     let formatter = NumberFormatter()
     formatter.numberStyle = .currency
-    formatter.currencyCode = "USD"
+    formatter.currencyCode = fiatCurrency
     formatter.locale = Locale(identifier: "en_US")
-    return formatter
-  }()
-
-  /// The current chain's balance in USD, when a price is known.
-  var fiatBalance: String? {
-    let price = chain == .xrp ? prices.xrp : prices.xmr
-    guard let price, let amount = Decimal(string: balance.total) else { return nil }
-    let usd = amount * Decimal(price)
-    return Self.fiatFormatter.string(from: usd as NSDecimalNumber)
+    return formatter.string(from: fiat as NSDecimalNumber)
   }
 
   private func refreshPrices() async {
-    prices = await PriceService.shared.prices()
+    prices = await PriceService.shared.prices(currency: fiatCurrency)
   }
 
   // MARK: - Biometric lock