ios: fix UI freezes on start and when exiting background (#3972)

* ios: fix UI freezes on start and when exiting background

* remove unused code

* comments

apps/ios/Shared/Model/SimpleXAPI.swift

@@ -21,6 +21,8 @@ public let CURRENT_CHAT_VERSION: Int = 2
 // version range that supports establishing direct connection with a group member (xGrpDirectInvVRange in core)
 public let CREATE_MEMBER_CONTACT_VRANGE = VersionRange(minVersion: 2, maxVersion: CURRENT_CHAT_VERSION)
 
+private let networkStatusesLock = DispatchQueue(label: "chat.simplex.app.network-statuses.lock")
+
 enum TerminalItem: Identifiable {
     case cmd(Date, ChatCommand)
     case resp(Date, ChatResponse)
@@ -1566,34 +1568,30 @@ func processReceivedMsg(_ res: ChatResponse) async {
                 m.removeChat(mergedContact.id)
             }
         }
-    case let .contactsSubscribed(_, contactRefs):
-        await updateContactsStatus(contactRefs, status: .connected)
-    case let .contactsDisconnected(_, contactRefs):
-        await updateContactsStatus(contactRefs, status: .disconnected)
-    case let .contactSubSummary(_, contactSubscriptions):
-        await MainActor.run {
-            for sub in contactSubscriptions {
-// no need to update contact here, and it is slow
-//                if active(user) {
-//                    m.updateContact(sub.contact)
-//                }
-                if let err = sub.contactError {
-                    processContactSubError(sub.contact, err)
-                } else {
-                    m.setContactNetworkStatus(sub.contact, .connected)
-                }
-            }
-        }
     case let .networkStatus(status, connections):
-        await MainActor.run {
+        // dispatch queue to synchronize access
+        networkStatusesLock.sync {
+            var ns = m.networkStatuses
+            // slow loop is on the background thread
             for cId in connections {
-                m.networkStatuses[cId] = status
+                ns[cId] = status
+            }
+            // fast model update is on the main thread
+            DispatchQueue.main.sync {
+                m.networkStatuses = ns
             }
         }
     case let .networkStatuses(_, statuses): ()
-        await MainActor.run {
+        // dispatch queue to synchronize access
+        networkStatusesLock.sync {
+            var ns = m.networkStatuses
+            // slow loop is on the background thread
             for s in statuses {
-                m.networkStatuses[s.agentConnId] = s.networkStatus
+                ns[s.agentConnId] = s.networkStatus
+            }
+            // fast model update is on the main thread
+            DispatchQueue.main.sync {
+                m.networkStatuses = ns
             }
         }
     case let .newChatItem(user, aChatItem):
@@ -1944,26 +1942,6 @@ func chatItemSimpleUpdate(_ user: any UserLike, _ aChatItem: AChatItem) async {
     }
 }
 
-func updateContactsStatus(_ contactRefs: [ContactRef], status: NetworkStatus) async {
-    let m = ChatModel.shared
-    await MainActor.run {
-        for c in contactRefs {
-            m.networkStatuses[c.agentConnId] = status
-        }
-    }
-}
-
-func processContactSubError(_ contact: Contact, _ chatError: ChatError) {
-    let m = ChatModel.shared
-    var err: String
-    switch chatError {
-    case .errorAgent(agentError: .BROKER(_, .NETWORK)): err = "network"
-    case .errorAgent(agentError: .SMP(smpErr: .AUTH)): err = "contact deleted"
-    default: err = String(describing: chatError)
-    }
-    m.setContactNetworkStatus(contact, .error(connectionError: err))
-}
-
 func refreshCallInvitations() throws {
     let m = ChatModel.shared
     let callInvitations = try justRefreshCallInvitations()

apps/ios/SimpleXChat/APITypes.swift

@@ -557,11 +557,6 @@ public enum ChatResponse: Decodable, Error {
     case contactRequestRejected(user: UserRef)
     case contactUpdated(user: UserRef, toContact: Contact)
     case groupMemberUpdated(user: UserRef, groupInfo: GroupInfo, fromMember: GroupMember, toMember: GroupMember)
-    // TODO remove events below
-    case contactsSubscribed(server: String, contactRefs: [ContactRef])
-    case contactsDisconnected(server: String, contactRefs: [ContactRef])
-    case contactSubSummary(user: UserRef, contactSubscriptions: [ContactSubStatus])
-    // TODO remove events above
     case networkStatus(networkStatus: NetworkStatus, connections: [String])
     case networkStatuses(user_: UserRef?, networkStatuses: [ConnNetworkStatus])
     case groupSubscribed(user: UserRef, groupInfo: GroupRef)
@@ -724,9 +719,6 @@ public enum ChatResponse: Decodable, Error {
             case .contactRequestRejected: return "contactRequestRejected"
             case .contactUpdated: return "contactUpdated"
             case .groupMemberUpdated: return "groupMemberUpdated"
-            case .contactsSubscribed: return "contactsSubscribed"
-            case .contactsDisconnected: return "contactsDisconnected"
-            case .contactSubSummary: return "contactSubSummary"
             case .networkStatus: return "networkStatus"
             case .networkStatuses: return "networkStatuses"
             case .groupSubscribed: return "groupSubscribed"
@@ -885,9 +877,6 @@ public enum ChatResponse: Decodable, Error {
             case .contactRequestRejected: return noDetails
             case let .contactUpdated(u, toContact): return withUser(u, String(describing: toContact))
             case let .groupMemberUpdated(u, groupInfo, fromMember, toMember): return withUser(u, "groupInfo: \(groupInfo)\nfromMember: \(fromMember)\ntoMember: \(toMember)")
-            case let .contactsSubscribed(server, contactRefs): return "server: \(server)\ncontacts:\n\(String(describing: contactRefs))"
-            case let .contactsDisconnected(server, contactRefs): return "server: \(server)\ncontacts:\n\(String(describing: contactRefs))"
-            case let .contactSubSummary(u, contactSubscriptions): return withUser(u, String(describing: contactSubscriptions))
             case let .networkStatus(status, conns): return "networkStatus: \(String(describing: status))\nconnections: \(String(describing: conns))"
             case let .networkStatuses(u, statuses): return withUser(u, String(describing: statuses))
             case let .groupSubscribed(u, groupInfo): return withUser(u, String(describing: groupInfo))

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/SimpleXAPI.kt

@@ -1753,6 +1753,8 @@ object ChatController {
           chatModel.removeChat(rhId, r.mergedContact.id)
         }
       }
+      // ContactsSubscribed, ContactsDisconnected and ContactSubSummary are only used in CLI,
+      // They have to be used here for remote desktop to process these status updates.
       is CR.ContactsSubscribed -> updateContactsStatus(r.contactRefs, NetworkStatus.Connected())
       is CR.ContactsDisconnected -> updateContactsStatus(r.contactRefs, NetworkStatus.Disconnected())
       is CR.ContactSubSummary -> {