"Real Time" Data - WatchKit

README.md

#Add To Project

Make sure to set the target to your app and to the WatchKit Extension

#Setup -- APP

In applicationDidFinishLaunching

Swift:

LGWatchKitListener.setGroupContainerIdentifier("group.<#YourGroupIdentifier#>")

ObjC:

[LGWatchKitListener setGroupContainerIdentifier:@"group.<#YourGroupIdentifier#>"];

#Setup -- WatchKit Extension

In initWithContext

Swift:

LGWatchKitListener.setGroupContainerIdentifier("group.<#YourGroupIdentifier#>")

ObjC:

[LGWatchKitListener setGroupContainerIdentifier:@"group.<#YourGroupIdentifier#>"];

#Listen

Swift:

LGWatchKitListener.startListeningForKey("test", withCallback: { (value, key) -> Void in
    println("Value: \(value) updatedForKey: \(key)")
})

ObjC:

[LGWatchKitListener startListeningForKey:@"test" withCallback: (id value, NSString *key)^{
    NSLog(@"Value: %@ updatedForKey: %@", value, key);
}];

LGWatchKitListener.swift

//
//  LGWatchKitListener.swift
//  RemoteCamera
//
//  Created by Logan Wright on 11/19/14.
//  Copyright (c) 2014 lowriDevs. All rights reserved.
//

import UIKit

// MARK: Listener Ref

class LGListenerRef : NSObject {
    var lastValue: NSObject?
    let callback: (value: NSObject?, key: String) -> Void
    init(lastValue: NSObject?, callback: (value: NSObject?, key: String) -> Void) {
        self.lastValue = lastValue
        self.callback = callback
    }
}

// MARK: Listener

class LGWatchKitListener: NSObject {
    
    // MARK: Identifier
    
    class func setGroupContainerIdentifier(groupContainerIdentifier: String) {
        Constants.GroupContainerIdentifier = groupContainerIdentifier
    }
    
    private struct Constants {
        static var GroupContainerIdentifier: String = ""
    }
    
    // MARK: Defaults Loader
    
    private lazy var defaults: NSUserDefaults = {
        if countElements(Constants.GroupContainerIdentifier) == 0 {
            fatalError("LGWatchKitListener: GroupContainerIdentifier Not Set Before Initializing Listener! You should call LGWatchKitListener.setGroupContainerIdentifier in your AppDelegate in appDidLoad")
        }
        return NSUserDefaults(suiteName: Constants.GroupContainerIdentifier)!
    }()
    
    // MARK: State Management
    
    private enum State {
        case Listening, Pending
    }
    
    // MARK: Private Properties
    
    private var state: State = .Pending
    private var listenerRefDictionary: [String : LGListenerRef] = [:]
    private var timer: NSTimer?
    
    // MARK: Singleton
    
    private class func sharedListener() -> LGWatchKitListener {
        struct Singleton {
            static let instance = LGWatchKitListener()
        }
        return Singleton.instance
    }
    
    // MARK: Listening Interaction
   
    class func startListeningForKey(key: String, withCallback callback: (value: NSObject?, key: String) -> Void) {
        self.sharedListener().listenerRefDictionary[key] = LGListenerRef(lastValue: nil, callback: callback)
        self.startListening()
    }
    
    class func stopListeningForKey(key: String) {
        self.sharedListener().listenerRefDictionary.removeValueForKey(key)
    }
    
    class func startListening() {
        if self.sharedListener().state == .Pending {
            self.sharedListener().state = .Listening
            self.sharedListener().timer?.invalidate()
            self.sharedListener().timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self.sharedListener(), selector: "timerFired:", userInfo: nil, repeats: true)
        }
    }
    
    class func stopListening() {
        self.sharedListener().timer?.invalidate()
        self.sharedListener().state = .Pending
    }
    
    class func removeAllListeningKeys() {
        self.stopListening()
        self.sharedListener().listenerRefDictionary = [:]
    }
    
    // MARK: Timer Handling
    
    func timerFired(timer: NSTimer) {
        for (key, listenerRef) in self.listenerRefDictionary {
            let currentValue: NSObject? = self.defaults.objectForKey(key) as? NSObject
            if currentValue != listenerRef.lastValue {
                self.listenerRefDictionary[key]?.lastValue = currentValue
                listenerRef.callback(value: currentValue, key: key)
            }
        }
    }
    
}