Add support for copy action

Closes venmo#80

Example/ViewController.swift

@@ -69,6 +69,11 @@ class ViewController: TableViewController {
                         self.showAlert(title: "Deleted.")
                     })
                 ])
+            ]),
+            Section(header: "Copying", rows: [
+                Row(text: "Tap and hold this row", copyAction: { [unowned self] row in
+                    self.showAlert(title: "Copied.")
+                })
             ])
         ]
     }

Static/DataSource.swift

@@ -277,4 +277,18 @@ extension DataSource: UITableViewDelegate {
             row.accessory.selection?()
         }
     }
+
+    public func tableView(tableView: UITableView, shouldShowMenuForRowAtIndexPath indexPath: NSIndexPath) -> Bool {
+        return rowForIndexPath(indexPath)?.canCopy ?? false
+    }
+
+    public func tableView(tableView: UITableView, canPerformAction action: Selector, forRowAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) -> Bool {
+        return action == #selector(NSObject.copy(_:)) && (rowForIndexPath(indexPath)?.canCopy ?? false)
+    }
+
+    public func tableView(tableView: UITableView, performAction action: Selector, forRowAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) {
+        if let row = rowForIndexPath(indexPath) where action == #selector(NSObject.copy(_:)) {
+            row.copyAction?(row)
+        }
+    }
 }

Static/Row.swift

@@ -3,6 +3,9 @@ import UIKit
 /// Row or Accessory selection callback.
 public typealias Selection = () -> Void
 
+/// Row copy callback
+public typealias CopyAction = (Row) -> Void
+
 /// Representation of a table row.
 public struct Row: Hashable, Equatable {
 
@@ -113,7 +116,14 @@ public struct Row: Hashable, Equatable {
 
     /// Actions to show when swiping the cell, such as Delete.
     public var editActions: [EditAction]
+
+    /// Action to run when the row is selected to copy
+    public var copyAction: CopyAction?
 
+    var canCopy: Bool {
+        return copyAction != nil
+    }
+
     var canEdit: Bool {
         return editActions.count > 0
     }
@@ -134,7 +144,7 @@ public struct Row: Hashable, Equatable {
     // MARK: - Initializers
 
     public init(text: String? = nil, detailText: String? = nil, selection: Selection? = nil,
-        image: UIImage? = nil, accessory: Accessory = .None, cellClass: CellType.Type? = nil, context: Context? = nil, editActions: [EditAction] = [], UUID: String = NSUUID().UUIDString) {
+                image: UIImage? = nil, accessory: Accessory = .None, cellClass: CellType.Type? = nil, context: Context? = nil, editActions: [EditAction] = [], copyAction: CopyAction? = nil, UUID: String = NSUUID().UUIDString) {
 
         self.UUID = UUID
         self.text = text
@@ -145,6 +155,7 @@ public struct Row: Hashable, Equatable {
         self.cellClass = cellClass ?? Value1Cell.self
         self.context = context
         self.editActions = editActions
+        self.copyAction = copyAction
     }
 }