implemented in RoomInfoListViewController

Riot/Assets/en.lproj/Vector.strings

@@ -479,6 +479,7 @@ Tap the + to start adding people.";
 "room_participants_invite_malformed_id" = "Malformed ID. Should be an email address or a Matrix ID like '@localpart:domain'";
 "room_participants_invited_section" = "INVITED";
 "room_participants_start_new_chat_error_using_user_email_without_identity_server" = "No identity server is configured so you cannot start a chat with a contact using an email.";
+"room_participants_leave_not_allowed_for_last_owner_msg" = "You can't leave the room since you're the only owner of it.";
 
 "room_participants_online" = "Online";
 "room_participants_offline" = "Offline";

Riot/Categories/MXRoom.swift

@@ -0,0 +1,33 @@
+// 
+// Copyright 2025 New Vector Ltd
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+@objc
+extension MXRoom {
+    /// Returns true if the user is the last owner of the room, but not the last member.
+    func isLastOwner() async throws -> Bool {
+        let userID = mxSession.myUserId
+        let state = try await state()
+        
+        guard RoomPowerLevelHelper.roomPowerLevel(from: state.powerLevelOfUser(withUserID: userID)) == .owner else {
+            return false
+        }
+        
+        guard let joinedMembers = try await members()?.members(with: .join) else {
+            return false
+        }
+        
+        var isLastMember = true
+        for member in joinedMembers where member.userId != userID {
+            isLastMember = false
+            // If there are other owners they can leave
+            if RoomPowerLevelHelper.roomPowerLevel(from: state.powerLevelOfUser(withUserID: member.userId)) == .owner {
+                return false
+            }
+        }
+        return !isLastMember
+    }
+}

Riot/Generated/Strings.swift

@@ -6447,6 +6447,10 @@ public class VectorL10n: NSObject {
   public static var roomParticipantsInvitedSection: String { 
     return VectorL10n.tr("Vector", "room_participants_invited_section") 
   }
+  /// You can't leave the room since you're the only owner of it
+  public static var roomParticipantsLeaveNotAllowedForLastOwnerMsg: String { 
+    return VectorL10n.tr("Vector", "room_participants_leave_not_allowed_for_last_owner_msg") 
+  }
   /// Leaving
   public static var roomParticipantsLeaveProcessing: String { 
     return VectorL10n.tr("Vector", "room_participants_leave_processing") 

Riot/Modules/Room/RoomInfo/RoomInfoList/RoomInfoListViewController.swift

@@ -75,6 +75,17 @@ final class RoomInfoListViewController: UIViewController {
         return controller
     }()
     
+    private lazy var isLastOwnerAlertController: UIAlertController = {
+        let title = VectorL10n.error
+        let message = VectorL10n.roomParticipantsLeaveNotAllowedForLastOwnerMsg
+        let controller = UIAlertController(title: title, message: message, preferredStyle: .alert)
+        
+        controller.addAction(UIAlertAction(title: VectorL10n.ok, style: .default, handler: nil))
+        controller.mxk_setAccessibilityIdentifier("RoomSettingsVCLastOwnerAlert")
+        
+        return controller
+    }()
+    
     private enum RowType {
         case `default`
         case destructive
@@ -216,7 +227,11 @@ final class RoomInfoListViewController: UIViewController {
             VectorL10n.roomParticipantsLeavePromptTitleForDm :
             VectorL10n.roomParticipantsLeavePromptTitle
         let rowLeave = Row(type: .destructive, icon: Asset.Images.roomActionLeave.image, text: leaveTitle, accessoryType: .none) {
-            self.present(self.leaveAlertController, animated: true, completion: nil)
+            if viewData.isLastOwner {
+                self.present(self.isLastOwnerAlertController, animated: true, completion: nil)
+            } else {
+                self.present(self.leaveAlertController, animated: true, completion: nil)
+            }
         }
         let sectionLeave = Section(header: nil,
                                    rows: [rowLeave],

Riot/Modules/Room/RoomInfo/RoomInfoList/RoomInfoListViewData.swift

@@ -24,4 +24,5 @@ struct RoomInfoListViewData {
     let isEncrypted: Bool
     let isDirect: Bool
     let basicInfoViewData: RoomInfoBasicViewData
+    let isLastOwner: Bool
 }

Riot/Modules/Room/RoomInfo/RoomInfoList/RoomInfoListViewModel.swift

@@ -26,6 +26,7 @@ final class RoomInfoListViewModel: NSObject, RoomInfoListViewModelType {
 
     private let session: MXSession
     private let room: MXRoom
+    private var isLastOwner = false
     
     // MARK: Public
 
@@ -51,7 +52,8 @@ final class RoomInfoListViewModel: NSObject, RoomInfoListViewModelType {
         return RoomInfoListViewData(numberOfMembers: Int(room.summary.membersCount.joined),
                                     isEncrypted: room.summary.isEncrypted,
                                     isDirect: room.isDirect,
-                                    basicInfoViewData: basicInfoViewData)
+                                    basicInfoViewData: basicInfoViewData,
+                                    isLastOwner: isLastOwner)
     }
     
     // MARK: - Setup
@@ -97,6 +99,9 @@ final class RoomInfoListViewModel: NSObject, RoomInfoListViewModelType {
     @objc private func roomSummaryUpdated(_ notification: Notification) {
         //  force update view
         self.update(viewState: .loaded(viewData: viewData))
+        Task {
+            isLastOwner = (try? await room.isLastOwner()) == true
+        }
     }
     
     private func loadData() {