WatchConnectivitySingletonDemo.swift

## WatchConnectivitySingletonDemo.swift
//
//  WatchSessionManager.swift
//  WatchConnectivityDemo
//
//  Created by Natasha Murashev on 9/3/15.
//  Copyright © 2015 NatashaTheRobot. All rights reserved.
//

import WatchConnectivity

class WatchSessionManager: NSObject, WCSessionDelegate {

    static let sharedManager = WatchSessionManager()
    private override init() {
        super.init()
    }

    private let session: WCSession? = WCSession.isSupported() ? WCSession.defaultSession() : nil

    private var validSession: WCSession? {

        // paired - the user has to have their device paired to the watch
        // watchAppInstalled - the user must have your watch app installed

        // Note: if the device is paired, but your watch app is not installed
        // consider prompting the user to install it for a better experience

        if let session = session where session.paired && session.watchAppInstalled {
            return session
        }
        return nil
    }

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

// MARK: Application Context
// use when your app needs only the latest information
// if the data was not sent, it will be replaced
extension WatchSessionManager {

    // Sender
    func updateApplicationContext(applicationContext: [String : AnyObject]) throws {
        if let session = validSession {
            do {
                try session.updateApplicationContext(applicationContext)
            } catch let error {
                throw error
            }
        }
    }

    // Receiver
    func session(session: WCSession, didReceiveApplicationContext applicationContext: [String : AnyObject]) {
        // handle receiving application context

        dispatch_async(dispatch_get_main_queue()) {
            // make sure to put on the main queue to update UI!
        }
    }
}

// MARK: User Info
// use when your app needs all the data
// FIFO queue
extension WatchSessionManager {

    // Sender
    func transferUserInfo(userInfo: [String : AnyObject]) -> WCSessionUserInfoTransfer? {
        return validSession?.transferUserInfo(userInfo)
    }

    func session(session: WCSession, didFinishUserInfoTransfer userInfoTransfer: WCSessionUserInfoTransfer, error: NSError?) {
        // implement this on the sender if you need to confirm that
        // the user info did in fact transfer
    }

    // Receiver
    func session(session: WCSession, didReceiveUserInfo userInfo: [String : AnyObject]) {
        // handle receiving user info
        dispatch_async(dispatch_get_main_queue()) {
            // make sure to put on the main queue to update UI!
        }
    }

}

// MARK: Transfer File
extension WatchSessionManager {

    // Sender
    func transferFile(file: NSURL, metadata: [String : AnyObject]) -> WCSessionFileTransfer? {
        return validSession?.transferFile(file, metadata: metadata)
    }

    func session(session: WCSession, didFinishFileTransfer fileTransfer: WCSessionFileTransfer, error: NSError?) {
        // handle filed transfer completion
    }

    // Receiver
    func session(session: WCSession, didReceiveFile file: WCSessionFile) {
        // handle receiving file
        dispatch_async(dispatch_get_main_queue()) {
            // make sure to put on the main queue to update UI!
        }
    }
}


// MARK: Interactive Messaging
extension WatchSessionManager {

    // Live messaging! App has to be reachable
    private var validReachableSession: WCSession? {
        if let session = validSession 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)
    }

    func sendMessageData(data: NSData,
        replyHandler: ((NSData) -> Void)? = nil,
        errorHandler: ((NSError) -> Void)? = nil)
    {
        validReachableSession?.sendMessageData(data, replyHandler: replyHandler, errorHandler: errorHandler)
    }

    // Receiver
    func session(session: WCSession, didReceiveMessage message: [String : AnyObject], replyHandler: ([String : AnyObject]) -> Void) {
        // handle receiving message
        dispatch_async(dispatch_get_main_queue()) {
            // make sure to put on the main queue to update UI!
        }
    }

    func session(session: WCSession, didReceiveMessageData messageData: NSData, replyHandler: (NSData) -> Void) {
        // handle receiving message data
        dispatch_async(dispatch_get_main_queue()) {
            // make sure to put on the main queue to update UI!
        }
    }
}