Cache wallet balance and activity so screens show it instantly

apps/ios/Koins/AppModel.swift

@@ -41,6 +41,27 @@ final class AppModel: ObservableObject {
 
   var symbol: String { chain.symbol }
 
+  // MARK: - Cache
+
+  /// Restores the last-known state for the chain on screen instantly; the
+  /// refresh that follows replaces it with live data.
+  private func showCached(_ forChain: Chain) {
+    guard let cached = WalletStore.cachedState(forChain) else { return }
+    balance = cached.balance
+    transactions = cached.transactions
+    if let accounts = cached.accounts { moneroAccounts = accounts }
+  }
+
+  private func persistState(for forChain: Chain) {
+    guard (forChain == .xrp ? xrpWallet : xmrWallet) != nil else { return }
+    WalletStore.saveCachedState(
+      ChainCache(balance: balance,
+                 transactions: transactions,
+                 accounts: forChain == .xmr ? moneroAccounts : nil,
+                 savedAt: Date()),
+      chain: forChain)
+  }
+
   // MARK: - Bootstrap
 
   func bootstrap() async {
@@ -57,6 +78,7 @@ final class AppModel: ObservableObject {
     if xrpWallet != nil || moneroReady {
       chain = xrpWallet != nil ? .xrp : .xmr
     }
+    showCached(chain)
     await refresh(force: true)
     startAutoRefresh()
   }
@@ -101,7 +123,9 @@ final class AppModel: ObservableObject {
     statusMessage = nil
     balance = Balance(total: "0", unlocked: "", funded: false)
     transactions = []
+    moneroAccounts = []
     syncStatus = nil
+    showCached(newChain)
 
     if newChain == .xmr, let xmrWallet, !moneroOpened {
       await openMonero(afterRestore: false, wallet: xmrWallet)
@@ -217,6 +241,7 @@ final class AppModel: ObservableObject {
         guard !isStale(token, requestChain) else { return }
         balance = fetchedBalance
         transactions = fetchedTransactions
+        persistState(for: requestChain)
       } catch {
         guard !isStale(token, requestChain) else { return }
         errorMessage = error.localizedDescription
@@ -251,6 +276,7 @@ final class AppModel: ObservableObject {
         balance = fetchedBalance
         transactions = fetchedTransactions
         moneroAccounts = fetchedAccounts
+        persistState(for: requestChain)
       }
     } catch {
       guard !isStale(token, requestChain) else { return }

apps/ios/Koins/Models.swift

@@ -18,12 +18,12 @@ struct WalletRecord: Codable, Identifiable, Equatable {
   var createdAt: Date
 }
 
-enum Direction {
+enum Direction: String, Codable {
   case incoming
   case outgoing
 }
 
-struct TransactionRecord: Identifiable {
+struct TransactionRecord: Identifiable, Codable {
   let id: String
   let amount: String
   let timestamp: Date?
@@ -44,12 +44,21 @@ struct TransactionRecord: Identifiable {
 
 }
 
-struct Balance {
+struct Balance: Codable {
   var total: String
   var unlocked: String
   var funded: Bool
 }
 
+/// Persisted per chain so a switch or relaunch shows the last-known state
+/// instantly while the network catches up.
+struct ChainCache: Codable {
+  var balance: Balance
+  var transactions: [TransactionRecord]
+  var accounts: [MoneroAccount]?
+  var savedAt: Date
+}
+
 struct SyncStatus {
   var height: UInt64
   var daemonHeight: UInt64
@@ -78,7 +87,7 @@ enum TransactionPriority: Int {
   }
 }
 
-struct MoneroSubaddress: Identifiable {
+struct MoneroSubaddress: Identifiable, Codable {
   let accountIndex: Int
   let index: Int
   let address: String
@@ -90,7 +99,7 @@ struct MoneroSubaddress: Identifiable {
   var id: String { "\(accountIndex)/\(index)" }
 }
 
-struct MoneroAccount: Identifiable {
+struct MoneroAccount: Identifiable, Codable {
   let index: Int
   let address: String
   let balance: String

apps/ios/Koins/Support/WalletStore.swift

@@ -63,9 +63,24 @@ enum WalletStore {
 
   static func removeWallet(_ chain: Chain) {
     defaults.removeObject(forKey: walletKey(chain))
+    defaults.removeObject(forKey: cacheKey(chain))
     Keychain.remove(secretKey(chain))
   }
 
+  // MARK: - Cached state (balance, transactions, accounts)
+
+  private static func cacheKey(_ chain: Chain) -> String { "koins.cache.\(chain.rawValue)" }
+
+  static func cachedState(_ chain: Chain) -> ChainCache? {
+    guard let data = defaults.data(forKey: cacheKey(chain)) else { return nil }
+    return try? JSONDecoder().decode(ChainCache.self, from: data)
+  }
+
+  static func saveCachedState(_ state: ChainCache, chain: Chain) {
+    guard let data = try? JSONEncoder().encode(state) else { return }
+    defaults.set(data, forKey: cacheKey(chain))
+  }
+
   static func secret(_ chain: Chain) -> String? {
     Keychain.get(secretKey(chain))
   }