Ensure graceful handling of DETACH and DISCONNECT.

Fixes #454.

Source/ARTRealtime.m

@@ -712,6 +712,7 @@ - (void)realtimeTransport:(id)transport didReceiveMessage:(ARTProtocolMessage *)
             // Event
             [self onConnected:message];
             break;
+        case ARTProtocolMessageDisconnect:
         case ARTProtocolMessageDisconnected:
             [self onDisconnected:message];
             break;

Source/ARTRealtimeChannel.m

@@ -357,6 +357,7 @@ - (void)onChannelMessage:(ARTProtocolMessage *)message {
         case ARTProtocolMessageAttached:
             [self setAttached:message];
             break;
+        case ARTProtocolMessageDetach:
         case ARTProtocolMessageDetached:
             [self setDetached:message];
             break;
@@ -413,7 +414,13 @@ - (void)setDetached:(ARTProtocolMessage *)message {
     }
     self.attachSerial = nil;
 
-    ARTStatus *reason = [ARTStatus state:ARTStateNotAttached info:[ARTErrorInfo createWithCode:0 message:@"channel has detached"]];
+    ARTErrorInfo *errorInfo;
+    if (message.error) {
+        errorInfo = message.error;
+    } else {
+        errorInfo = [ARTErrorInfo createWithCode:0 message:@"channel has detached"];
+    }
+    ARTStatus *reason = [ARTStatus state:ARTStateNotAttached info:errorInfo];
     [self detachChannel:reason];
     [_detachedEventEmitter emit:[NSNull null] with:nil];
 }

Spec/RealtimeClientChannel.swift

@@ -2407,6 +2407,32 @@ class RealtimeClientChannel: QuickSpec {
                     }
                 }
             }
+
+            // https://github.com/ably/ably-ios/issues/454
+            it("should not move to FAILED if received DETACH with an error") {
+                let options = AblyTests.commonAppSetup()
+                let client = ARTRealtime(options: options)
+                defer {
+                    client.dispose()
+                    client.close()
+                }
+                let channel = client.channels.get("test")
+                channel.attach()
+
+                expect(channel.state).toEventually(equal(ARTRealtimeChannelState.Attached), timeout: testTimeout)
+
+                let protoMsg = ARTProtocolMessage()
+                protoMsg.action = .Detach
+                protoMsg.error = ARTErrorInfo.createWithCode(123, message: "test error")
+                protoMsg.channel = "test"
+
+                client.realtimeTransport(client.transport, didReceiveMessage: protoMsg)
+
+                expect(channel.state).to(equal(ARTRealtimeChannelState.Detached))
+                expect(channel.errorReason).to(equal(protoMsg.error))
+                expect(client.connection.state).to(equal(ARTRealtimeConnectionState.Connected))
+                expect(client.connection.errorReason).to(beNil())
+            }
         }
     }
 }

Spec/RealtimeClientConnection.swift

@@ -2943,6 +2943,26 @@ class RealtimeClientConnection: QuickSpec {
 
             }
 
+            // https://github.com/ably/ably-ios/issues/454
+            it("should not move to FAILED if received DISCONNECT with an error") {
+                let options = AblyTests.commonAppSetup()
+                let client = ARTRealtime(options: options)
+                defer {
+                    client.dispose()
+                    client.close()
+                }
+
+                expect(client.connection.state).toEventually(equal(ARTRealtimeConnectionState.Connected), timeout: testTimeout)
+
+                let protoMsg = ARTProtocolMessage()
+                protoMsg.action = .Disconnect
+                protoMsg.error = ARTErrorInfo.createWithCode(123, message: "test error")
+
+                client.realtimeTransport(client.transport, didReceiveMessage: protoMsg)
+
+                expect(client.connection.state).to(equal(ARTRealtimeConnectionState.Disconnected))
+                expect(client.connection.errorReason).to(equal(protoMsg.error))
+            }
         }
     }
 }