Add tasks for all the new languages

Task/Priority-queue/Swift/priority-queue.swift

@@ -0,0 +1,56 @@
+class Task : Comparable, CustomStringConvertible {
+  var priority : Int
+  var name: String
+  init(priority: Int, name: String) {
+    self.priority = priority
+    self.name = name
+  }
+  var description: String {
+    return "\(priority), \(name)"
+  }
+}
+func ==(t1: Task, t2: Task) -> Bool {
+  return t1.priority == t2.priority
+}
+func <(t1: Task, t2: Task) -> Bool {
+  return t1.priority < t2.priority
+}
+
+struct TaskPriorityQueue {
+  let heap : CFBinaryHeapRef = {
+    var callBacks = CFBinaryHeapCallBacks(version: 0, retain: {
+      UnsafePointer(Unmanaged<Task>.fromOpaque(COpaquePointer($1)).retain().toOpaque())
+      }, release: {
+        Unmanaged<Task>.fromOpaque(COpaquePointer($1)).release()
+      }, copyDescription: nil, compare: { (ptr1, ptr2, _) in
+        let t1 : Task = Unmanaged<Task>.fromOpaque(COpaquePointer(ptr1)).takeUnretainedValue()
+        let t2 : Task = Unmanaged<Task>.fromOpaque(COpaquePointer(ptr2)).takeUnretainedValue()
+        return t1 == t2 ? CFComparisonResult.CompareEqualTo : t1 < t2 ? CFComparisonResult.CompareLessThan : CFComparisonResult.CompareGreaterThan
+    })
+    return CFBinaryHeapCreate(nil, 0, &callBacks, nil)
+  }()
+  var count : Int { return CFBinaryHeapGetCount(heap) }
+  mutating func push(t: Task) {
+    CFBinaryHeapAddValue(heap, UnsafePointer(Unmanaged.passUnretained(t).toOpaque()))
+  }
+  func peek() -> Task {
+    return Unmanaged<Task>.fromOpaque(COpaquePointer(CFBinaryHeapGetMinimum(heap))).takeUnretainedValue()
+  }
+  mutating func pop() -> Task {
+    let result = Unmanaged<Task>.fromOpaque(COpaquePointer(CFBinaryHeapGetMinimum(heap))).takeUnretainedValue()
+    CFBinaryHeapRemoveMinimumValue(heap)
+    return result
+  }
+}
+
+var pq = TaskPriorityQueue()
+
+pq.push(Task(priority: 3, name: "Clear drains"))
+pq.push(Task(priority: 4, name: "Feed cat"))
+pq.push(Task(priority: 5, name: "Make tea"))
+pq.push(Task(priority: 1, name: "Solve RC tasks"))
+pq.push(Task(priority: 2, name: "Tax return"))
+
+while pq.count != 0 {
+  print(pq.pop())
+}