Restore contacts from backup

XXClient library

• Improve error handling in UdMultiLookupCallback.

xx-messenger example

• Improve backup restoration.
• Restore contacts.
• Add contact lookup feature.
• Display contact ids.
• Improve sending requests.
• Restore username from restored facts, not from restored params.

Examples/xx-messenger/Sources/ContactLookupFeature/ContactLookupFeature.swift

+import ComposableArchitecture
+import Foundation
+import XCTestDynamicOverlay
+import XXClient
+import XXMessengerClient
+
+public struct ContactLookupState: Equatable {
+  public init(
+    id: Data,
+    isLookingUp: Bool = false,
+    failure: String? = nil
+  ) {
+    self.id = id
+    self.isLookingUp = isLookingUp
+    self.failure = failure
+  }
+
+  public var id: Data
+  public var isLookingUp: Bool
+  public var failure: String?
+}
+
+public enum ContactLookupAction: Equatable {
+  case lookupTapped
+  case didLookup(XXClient.Contact)
+  case didFail(NSError)
+}
+
+public struct ContactLookupEnvironment {
+  public init(
+    messenger: Messenger,
+    mainQueue: AnySchedulerOf<DispatchQueue>,
+    bgQueue: AnySchedulerOf<DispatchQueue>
+  ) {
+    self.messenger = messenger
+    self.mainQueue = mainQueue
+    self.bgQueue = bgQueue
+  }
+
+  public var messenger: Messenger
+  public var mainQueue: AnySchedulerOf<DispatchQueue>
+  public var bgQueue: AnySchedulerOf<DispatchQueue>
+}
+
+#if DEBUG
+extension ContactLookupEnvironment {
+  public static let unimplemented = ContactLookupEnvironment(
+    messenger: .unimplemented,
+    mainQueue: .unimplemented,
+    bgQueue: .unimplemented
+  )
+}
+#endif
+
+public let contactLookupReducer = Reducer<ContactLookupState, ContactLookupAction, ContactLookupEnvironment>
+{ state, action, env in
+  switch action {
+  case .lookupTapped:
+    state.isLookingUp = true
+    state.failure = nil
+    return Effect.result { [state] in
+      do {
+        let contact = try env.messenger.lookupContact(id: state.id)
+        return .success(.didLookup(contact))
+      } catch {
+        return .success(.didFail(error as NSError))
+      }
+    }
+    .subscribe(on: env.bgQueue)
+    .receive(on: env.mainQueue)
+    .eraseToEffect()
+
+  case .didLookup(_):
+    state.isLookingUp = false
+    state.failure = nil
+    return .none
+
+  case .didFail(let error):
+    state.isLookingUp = false
+    state.failure = error.localizedDescription
+    return .none
+  }
+}