Cache room display names

ElementX/Sources/AppCoordinator.swift

@@ -134,7 +134,7 @@ class AppCoordinator: AuthenticationCoordinatorDelegate, Coordinator {
                                                         memberDetailProvider: memberDetailProvider)
         
         let parameters = RoomScreenCoordinatorParameters(timelineController: timelineController,
-                                                         roomName: roomProxy.name)
+                                                         roomName: roomProxy.displayName ?? roomProxy.name)
         let coordinator = RoomScreenCoordinator(parameters: parameters)
         
         self.add(childCoordinator: coordinator)

ElementX/Sources/Services/Room/MockRoomProxy.swift

@@ -12,7 +12,7 @@ import Combine
 struct MockRoomProxy: RoomProxyProtocol {
     let id = UUID().uuidString
     let name: String? = nil
-    let displayName: String
+    let displayName: String?
     
     let topic: String? = nil
     let messages: [RoomMessageProtocol] = []
@@ -28,7 +28,7 @@ struct MockRoomProxy: RoomProxyProtocol {
     var callbacks = PassthroughSubject<RoomProxyCallback, Never>()
     
     func displayName(_ completion: @escaping (Result<String, RoomProxyError>) -> Void) {
-        completion(.success(displayName))
+        completion(.success("Room display name"))
     }
     
     func startLiveEventListener() {

ElementX/Sources/Services/Room/RoomProxy.swift

@@ -36,6 +36,8 @@ class RoomProxy: RoomProxyProtocol {
     
     private var backwardStream: BackwardsStreamProtocol?
     
+    private(set) var displayName: String?
+    
     let callbacks = PassthroughSubject<RoomProxyCallback, Never>()
     
     private(set) var messages: [RoomMessageProtocol]
@@ -126,9 +128,15 @@ class RoomProxy: RoomProxyProtocol {
     }
     
     func displayName(_ completion: @escaping (Result<String, RoomProxyError>) -> Void) {
+        if let displayName = displayName {
+            completion(.success(displayName))
+            return
+        }
+        
         generalProcessingQueue.async {
             do {
                 let displayName = try self.room.displayName()
+                self.displayName = displayName
 
                 DispatchQueue.main.async {
                     completion(.success(displayName))

ElementX/Sources/Services/Room/RoomProxyProtocol.swift

@@ -30,6 +30,7 @@ protocol RoomProxyProtocol {
     var isTombstoned: Bool { get }
     
     var name: String? { get }
+    var displayName: String? { get }
     
     var topic: String? { get }
     var messages: [RoomMessageProtocol] { get }