Add a variadic method for emit completion handlers in swift

Source/SocketIO/Client/SocketIOClient.swift

@@ -221,6 +221,18 @@ open class SocketIOClient : NSObject, SocketIOClientSpec {
             handleClientEvent(.error, data: [event, items, error])
         }
     }
+    
+    /// Send an event to the server, with optional data items and write completion handler.
+    ///
+    /// If an error occurs trying to transform `items` into their socket representation, a `SocketClientEvent.error`
+    /// will be emitted. The structure of the error data is `[eventName, items, theError]`
+    ///
+    /// - parameter event: The event to send.
+    /// - parameter items: The items to send with this event. May be left out.
+    /// - parameter completion: Callback called on transport write completion.
+    open func emit(_ event: String, _ items: SocketData..., completion: @escaping () -> ())  {
+        emit([event] + items, completion: completion)
+    }
 
     /// Same as emit, but meant for Objective-C
     ///

Source/SocketIO/Client/SocketIOClientSpec.swift

@@ -101,6 +101,16 @@ public protocol SocketIOClientSpec : AnyObject {
     /// - parameter items: The items to send with this event. May be left out.
     func emit(_ event: String, _ items: SocketData...)
 
+    /// Send an event to the server, with optional data items and write completion handler.
+    ///
+    /// If an error occurs trying to transform `items` into their socket representation, a `SocketClientEvent.error`
+    /// will be emitted. The structure of the error data is `[eventName, items, theError]`
+    ///
+    /// - parameter event: The event to send.
+    /// - parameter items: The items to send with this event. May be left out.
+    /// - parameter completion: Callback called on transport write completion.
+    func emit(_ event: String, _ items: SocketData..., completion: @escaping () -> ())
+
     /// Call when you wish to tell the server that you've received the event for `ack`.
     ///
     /// - parameter ack: The ack number.

Tests/TestSocketIO/SocketSideEffectTest.swift

@@ -27,6 +27,11 @@ class SocketSideEffectTest: XCTestCase {
         XCTAssertEqual(socket.currentAck, 1)
     }
 
+    func testEmitCompletionSyntax() {
+        socket.emit("test", completion: {})
+        socket.emit("test", "thing", completion: {})
+    }
+
     func testHandleAck() {
         let expect = expectation(description: "handled ack")
         socket.emitWithAck("test").timingOut(after: 0) {data in