PickerをPopoverで表示するライブラリの紹介 ref: http://qiita.com/hsylife/items/e54ae8bde0838db53ae3

file0.swift

let displayStringFor:((String?)->String?)? = { string in
   if let s = string {
      switch(s){
      case "value 1":
        return "😊"
      case "value 2":
         return "😏"
      case "value 3":
         return "😓"
      default:
         return s
      }
    }
  return nil
  }

  StringPickerPopover.appearFrom(
   originView: button,
   baseViewController: self,
   title: "StringPicker",
   choices: ["value 1","value 2","value 3"],
   displayStringFor: displayStringFor,
   initialRow:0,
   doneAction: { selectedRow, selectedString in print("done row \(selectedRow) \(selectedString)")} ,
   cancelAction: { print("cancel")}
  )