Using openParentApplication:reply: to pass Strings

InterfaceController.swift

import WatchKit
import Foundation

class InterfaceController: WKInterfaceController {

    @IBAction func ButtonPress() {
        
        var userInfo: [NSObject: AnyObject] = [:]
        userInfo["request"] = "This is a string"
        
        // send a request String to the parent application
        // expect a response String in return
        WKInterfaceController.openParentApplication(userInfo, reply: {(reply, error) -> Void in
            if let response: String = reply?["response"] as? String {
                println("response: \(response)")
            } else {
                println("response received but not recognised")
            }
        })
    }

}