PhoneSessionManager.swift

//
//  PhoneSessionManager.swift
//

import WatchConnectivity

class PhoneSessionManager: NSObject, WCSessionDelegate {

  static let sharedManager = PhoneSessionManager()
  
  // Reference to the model object.
  private var shelterSummary = ShelterSummary()
  private let session: WCSession? = WCSession.isSupported() ? WCSession.defaultSession() : nil

  func startSession() {
    session?.delegate = self
    session?.activateSession()
  }

  func requestApplicationContext() {
    // Send a message with a key that your phone expects. You can organize your constants in a
    // series of structs like I did, or hard code a string instead of Key.Request.ApplicationContext.
    sendMessage([Key.Request.ApplicationContext: true], replyHandler: nil, errorHandler: nil)
  }
  
  func sessionReachabilityDidChange(session: WCSession) {
    // Request new application context when reachability changes.
    requestApplicationContext()
  }
  
}

// MARK: Application Context
extension PhoneSessionManager {

  // Receiver
  func session(session: WCSession, didReceiveApplicationContext applicationContext: [String : AnyObject]) {
    dispatch_async(dispatch_get_main_queue()) { [weak self] in
      // Update the model object.
      self?.shelterSummary.updateFromContext(applicationContext)
    }
  }

}


// MARK: Interactive Messaging
extension PhoneSessionManager {

  // App has to be reachable for live messaging.
  private var validReachableSession: WCSession? {
    if let session = session where session.reachable {
      return session
    }
    return nil
  }

  // Sender
  func sendMessage(message: [String : AnyObject], replyHandler: (([String : AnyObject]) -> Void)? = nil,
    errorHandler: ((NSError) -> Void)? = nil) {
    validReachableSession?.sendMessage(message, replyHandler: replyHandler, errorHandler: errorHandler)
  }
  
}