Receive doubly encoded utf8 in polling until https://github.com/Automattic/engine.io/issues/315 is fixed properly

SwiftIO/SocketEngine.swift

@@ -179,7 +179,7 @@ public class SocketEngine: NSObject, WebSocketDelegate {
             
             // println(data)
             
-            if let str = NSString(data: data, encoding: NSUTF8StringEncoding) {
+            if var str = NSString(data: data, encoding: NSUTF8StringEncoding) as? String {
                 dispatch_async(self!.parseQueue) {callback(str)}
             }
             
@@ -221,6 +221,7 @@ public class SocketEngine: NSObject, WebSocketDelegate {
         
         for packet in self.postWait {
             let len = countElements(packet)
+            
             postStr += "\(len):\(packet)"
         }
         
@@ -405,6 +406,7 @@ public class SocketEngine: NSObject, WebSocketDelegate {
     
     private func parseEngineMessage(var message:String) {
         // NSLog("Engine got message: \(message)")
+        fixDoubleUTF8(&message)
         
         // We should upgrade
         if message == "3probe" {
@@ -582,4 +584,4 @@ public class SocketEngine: NSObject, WebSocketDelegate {
     public func websocketDidReceiveData(socket:WebSocket, data:NSData) {
         self.parseEngineData(data)
     }
-}
+}

SwiftIO/SocketFixUTF8.swift

@@ -0,0 +1,100 @@
+//
+//  SocketFixUTF8.swift
+//  Socket.IO-Swift
+//
+//  Created by Erik Little on 3/16/15.
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+// Adapted from: https://github.com/durbrow/fix-double-utf8.swift
+
+import Foundation
+
+var memoizer = [String: UnicodeScalar]()
+
+func lookup(base:UnicodeScalar, combi:UnicodeScalar) -> UnicodeScalar {
+    let combined = "\(base)\(combi)"
+    
+    if let y = memoizer[combined] {
+        return y
+    }
+    
+    for i in 0x80...0xFF {
+        let ch = UnicodeScalar(i)
+        
+        if String(ch) == combined {
+            memoizer[combined] = ch
+            return ch
+        }
+    }
+    let ch = UnicodeScalar(0xFFFD) // Unicode replacement character <EFBFBD>
+    
+    memoizer[combined] = ch
+    return ch
+}
+
+func fixDoubleUTF8(inout name:String) {
+    var isASCII = true
+    var y = [UInt8]()
+    
+    for ch in name.unicodeScalars {
+        if ch.value < 0x80 {
+            y.append(UInt8(ch))
+            continue
+        }
+        isASCII = false
+        
+        if ch.value < 0x100 {
+            y.append(UInt8(ch))
+            continue
+        }
+        // might be a combining character that when combined with the
+        // preceeding character maps to a codepoint in the UTF8 range
+        if y.count == 0 {
+            return
+        }
+        
+        let last = y.removeLast()
+        let repl = lookup(UnicodeScalar(last), ch)
+        
+        // the replacement needs to be in the UTF8 range
+        if repl.value >= 0x100 {
+            return
+        }
+        
+        y.append(UInt8(repl))
+    }
+    
+    if isASCII {
+        return
+    }
+    
+    y.append(0) // null terminator
+    
+    return y.withUnsafeBufferPointer {
+        let cstr = UnsafePointer<CChar>($0.baseAddress) // typecase from uint8_t * to char *
+        let rslt = String.fromCStringRepairingIllFormedUTF8(cstr) // -> (String, Bool)
+        if let str = rslt.0 {
+            if !rslt.hadError {
+                name = str
+            }
+        }
+        
+        return
+    }
+}