From a72f96759e96091986af3785346406d063622165 Mon Sep 17 00:00:00 2001
From: Kevin Jose Martin <kevin@tiliq.com>
Date: Thu, 17 Sep 2015 18:19:49 -0400
Subject: [PATCH] Adds SocketIOClient#once(event, callback)

When the specified event is emitted, the handler deregisters itself.
---
 SocketIOClientSwift/SocketIOClient.swift | 28 ++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/SocketIOClientSwift/SocketIOClient.swift b/SocketIOClientSwift/SocketIOClient.swift
index cd52b69..aa6fdf8 100644
--- a/SocketIOClientSwift/SocketIOClient.swift
+++ b/SocketIOClientSwift/SocketIOClient.swift
@@ -424,6 +424,34 @@ public final class SocketIOClient: NSObject, SocketEngineClient {
         handlers.append(handler)
     }
     
+    /**
+    Adds a single-use handler for an event.
+    */
+    public func once(event: String, callback: NormalCallback) {
+        Logger.log("Adding once handler for event: %@", type: logType, args: event)
+        
+        let handler = SocketEventHandler(event: event) { data: NSArray?, ack: AckEmitter? in
+            handlers = ContiguousArray(handlers.filter { $0 != handler })
+            callback?(data, ack)
+        }
+
+        handlers.append(handler)
+    }
+    
+    /**
+    Adds a single-use handler for an event.
+    */
+    public func once(event event: String, callback: NormalCallbackObjectiveC) {
+        Logger.log("Adding once handler for event: %@", type: logType, args: event)
+        
+        let handler = SocketEventHandler(event: event) { data: NSArray?, ack: AckEmitterObjectiveC? in
+            handlers = ContiguousArray(handlers.filter { $0 != handler })
+            callback?(data, ack)
+        }
+
+        handlers.append(handler)
+    }
+    
     /**
     Removes all handlers.
     Can be used after disconnecting to break any potential remaining retain cycles.