Add tasks for all the new languages

Task/Determine-if-only-one-instance-is-running/Swift/determine-if-only-one-instance-is-running.swift

@@ -0,0 +1,26 @@
+import Foundation
+
+let globalCenter = NSDistributedNotificationCenter.defaultCenter()
+let time = NSDate().timeIntervalSince1970
+
+globalCenter.addObserverForName("OnlyOne", object: nil, queue: NSOperationQueue.mainQueue()) {not in
+    if let senderTime = not.userInfo?["time"] as? NSTimeInterval where senderTime != time {
+        println("More than one running")
+        exit(0)
+    } else {
+        println("Only one")
+    }
+}
+
+func send() {
+    globalCenter.postNotificationName("OnlyOne", object: nil, userInfo: ["time": time])
+
+    let waitTime = dispatch_time(DISPATCH_TIME_NOW, Int64(3 * NSEC_PER_SEC))
+
+    dispatch_after(waitTime, dispatch_get_main_queue()) {
+        send()
+    }
+}
+
+send()
+CFRunLoopRun()