Just use one boolean to determine polling/ws

Source/SocketIO/Engine/SocketEngine.swift

@@ -112,6 +112,7 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
     public private(set) var urlWebSocket = URL(string: "http://localhost/")!
 
     /// If `true`, then the engine is currently in WebSockets mode.
+    @available(*, deprecated, message: "No longer needed, if we're not polling, then we must be doing websockets")
     public private(set) var websocket = false
 
     /// The WebSocket for this engine.
@@ -233,7 +234,6 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
 
         if forceWebsockets {
             polling = false
-            websocket = true
             createWebSocketAndConnect()
             return
         }
@@ -312,19 +312,15 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
     }
 
     private func _disconnect(reason: String) {
-        guard connected else { return closeOutEngine(reason: reason) }
+        guard connected && !closed else { return closeOutEngine(reason: reason) }
 
         DefaultSocketLogger.Logger.log("Engine is being closed.", type: SocketEngine.logType)
 
-        if closed {
+        if polling {
-            return closeOutEngine(reason: reason)
+            disconnectPolling(reason: reason)
-        }
+        } else {
-
-        if websocket {
             sendWebSocketMessage("", withType: .close, withData: [])
             closeOutEngine(reason: reason)
-        } else {
-            disconnectPolling(reason: reason)
         }
     }
 
@@ -347,8 +343,9 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
                 "we'll probably disconnect soon. You should report this.", type: SocketEngine.logType)
         }
 
+        DefaultSocketLogger.Logger.log("Switching to WebSockets", type: SocketEngine.logType)
+
         sendWebSocketMessage("", withType: .upgrade, withData: [])
-        websocket = true
         polling = false
         fastUpgrade = false
         probing = false
@@ -443,6 +440,9 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
 
         // We should upgrade
         if message == "3probe" {
+            DefaultSocketLogger.Logger.log("Received probe response, should upgrade to WebSockets",
+                                           type: SocketEngine.logType)
+
             upgradeTransport()
         }
 
@@ -509,7 +509,6 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
         sid = ""
         waitingForPoll = false
         waitingForPost = false
-        websocket = false
     }
 
     private func sendPing() {
@@ -592,17 +591,20 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
     public func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data]) {
         engineQueue.async {
             guard self.connected else { return }
+            guard !self.probing else {
+                self.probeWait.append((msg, type, data))
 
-            if self.websocket {
+                return
-                DefaultSocketLogger.Logger.log("Writing ws: \(msg) has data: \(data.count != 0)",
+            }
-                                               type: SocketEngine.logType)
+
-                self.sendWebSocketMessage(msg, withType: type, withData: data)
+            if self.polling {
-            } else if !self.probing {
                 DefaultSocketLogger.Logger.log("Writing poll: \(msg) has data: \(data.count != 0)",
                                                type: SocketEngine.logType)
                 self.sendPollMessage(msg, withType: type, withData: data)
             } else {
-                self.probeWait.append((msg, type, data))
+                DefaultSocketLogger.Logger.log("Writing ws: \(msg) has data: \(data.count != 0)",
+                                               type: SocketEngine.logType)
+                self.sendWebSocketMessage(msg, withType: type, withData: data)
             }
         }
     }
@@ -631,14 +633,14 @@ public final class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePoll
             return
         }
 
-        guard websocket else {
+        guard !polling else {
             flushProbeWait()
 
             return
         }
 
         connected = false
-        websocket = false
+        polling = true
 
         if let reason = error?.localizedDescription {
             didError(reason: reason)

Source/SocketIO/Engine/SocketEnginePollable.swift

@@ -101,7 +101,7 @@ extension SocketEnginePollable {
     ///
     /// You shouldn't need to call this directly, the engine should automatically maintain a long-poll request.
     public func doPoll() {
-        guard !websocket && !waitingForPoll && connected && !closed else { return }
+        guard polling && !waitingForPoll && connected && !closed else { return }
 
         var req = URLRequest(url: urlPollingWithSid)
         addHeaders(to: &req)
@@ -151,7 +151,7 @@ extension SocketEnginePollable {
 
     private func flushWaitingForPost() {
         guard postWait.count != 0 && connected else { return }
-        guard !websocket else {
+        guard polling else {
             flushWaitingForPostToWebSocket()
 
             return

Source/SocketIO/Engine/SocketEngineSpec.swift

@@ -82,6 +82,7 @@ import Starscream
     var urlWebSocket: URL { get }
 
     /// If `true`, then the engine is currently in WebSockets mode.
+    @available(*, deprecated, message: "No longer needed, if we're not polling, then we must be doing websockets")
     var websocket: Bool { get }
 
     /// The WebSocket for this engine.
@@ -169,10 +170,10 @@ extension SocketEngineSpec {
     }
 
     func createBinaryDataForSend(using data: Data) -> Either<Data, String> {
-        if websocket {
+        if polling {
-            return .left(Data(bytes: [0x4]) + data)
-        } else {
             return .right("b4" + data.base64EncodedString(options: Data.Base64EncodingOptions(rawValue: 0)))
+        } else {
+            return .left(Data(bytes: [0x4]) + data)
         }
     }