How do I check if the same item exist in plist and SpriteKit?

I am trying to make a RPG game in IOS, with a similar dialogue system in Baldurs Gate. I have created two arrays in a plist file. Like this:

Plist file

As you can see I have two arrays: PlayerMessage; a list (it will be) of multiple choices that the player can touch and NPCMessages; the text that is displayed when the PlayerMessage is touched

I am at the stage where I can touch on the NPC and see a black box with text from array (PlayerMessage). However I do not know how to tell Swift, if a player touches the string of the Item in PlayerMessage and if same item exist in NPC Message display the string of that item.

Here is the code that I have used:

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {          for touch in (touches) {                  NPC.name = "NPC"                  let Location = touch.location(in: self)                                          var CorrectedLocation = CGPoint()                     CorrectedLocation.x = Location.x - LocalCamera.position.x                     CorrectedLocation.y = Location.y - LocalCamera.position.y          let node = self.atPoint(CorrectedLocation)         var Message: SKLabelNode!         Message = SKLabelNode(fontNamed: "Trebuchet MS")          if (node.name == "NPC") {             let NPCMessageer = SKSpriteNode (color: UIColor.black, size: CGSize(width:1000, height:1000))             NPCMessageer.zPosition = 99             NPCMessageer.position = CGPoint(x:-500, y:-200)           Message.fontSize = 50             Message.color = UIColor.white;            Message.position = CGPoint(x:-500, y:-100)             Message.zPosition = 100              addChild(NPCMessageer)             self.addChild(Message)             for PlayerMessage in NPC.PlayerMessage {              Message.text = PlayerMessage as?String}             let label = self.atPoint(CorrectedLocation)             if label.name == "Message"             {                                                if NPC.PlayerMessage == NPC.NPCMessage              {                 Message.text = NPC.NPCMessage as?String              }