Losing reference to a property of an instance in Swift - ios

Question

I'm encountering a problem where a property of an instance of a class I've created is seemingly losing reference to one its values.
Essentially I have a class like this:
class Channel {
var callbacks: [String: (JSON) -> Void]
var subscribed = false
let name: String
init(name: String) {
self.name = name
self.callbacks = [:]
}
func bind(eventName: String, callback: (JSON) -> Void) {
self.callbacks[eventName] = callback
}
func handleEvent(eventName: String, eventData: String) {
if let cb = self.callbacks[eventName] {
let json = JSON(object: eventData)
cb(json)
}
}
}
and then inside a ViewController I have the following code:
class ViewController: UIViewController {
let wSock = wSocket(key: "afa4d38348f89ba9c398")
func channelSetup() {
var ch = wSock.subscribe("test-channel")
ch.bind("test-event", { (data: JSON) -> Void in
println("I'm the callback getting called")
})
println(ch.callbacks)
}
override func viewDidLoad() {
super.viewDidLoad()
channelSetup()
}
}
In the println of ch.callbacks it shows that there is a key-value pair in the dictionary.
However, when the channel receives an event later on when there is a message received over the socket, the callback is no longer there. In terms of code, here is the code in full:
import UIKit
class ViewController: UIViewController {
let wSock = wSocketClient(key: "afa4d38348f89ba9c398")
func channelSetup() {
var ch = wSock.subscribe("test-channel")
ch.bind("test-event", { (data: JSON) -> Void in
println("I'm the callback getting called")
})
println(ch.callbacks)
}
override func viewDidLoad() {
super.viewDidLoad()
channelSetup()
}
}
class wSocketClient {
let connection: Connection
init(key: String, encrypted: Bool = false) {
var url = "SOCKET_URL"
connection = Connection(url: url)
}
func subscribe(channelName: String) -> Channel {
return self.connection.addChannel(channelName)
}
func connect() {
self.connection.open()
}
}
class Connection: WebSocketDelegate {
let url: String
lazy var socket: WebSocket = { [unowned self] in
return self.connectInternal()
}()
let connected = false
var channels = Channels()
init(url: String) {
self.url = url
}
func addChannel(channelName: String) -> Channel {
return Channel(name: channelName)
}
func open() {
if self.connected {
return
} else {
self.socket = connectInternal()
}
}
func connectInternal() -> WebSocket {
let ws = WebSocket(url: NSURL(string: self.url)!)
ws.delegate = self
ws.connect()
return ws
}
func websocketDidReceiveMessage(text: String) {
let data = (text as NSString).dataUsingEncoding(NSUTF8StringEncoding)
let json = JSON(data: data!)
if let channelName = json["channel"].stringValue {
if let internalChannel = self.channels.find(channelName) {
if let eName = json["event"].stringValue {
if let eData = json["data"].stringValue {
internalChannel.handleEvent(eName, eventData: eData) // this is the part of the code where the channel should eventually call the callback
}
}
}
}
}
}
class Channel {
var callbacks: [String: (JSON) -> Void]
var subscribed = false
let name: String
init(name: String) {
self.name = name
self.callbacks = [:]
}
func bind(eventName: String, callback: (JSON) -> Void) {
self.callbacks[eventName] = callback
}
func handleEvent(eventName: String, eventData: String) {
if let cb = self.callbacks[eventName] { // here self.callbacks is empty and the callback has disappeared
let json = JSON(object: eventData)
cb(json)
}
}
}
class Channels {
var channels = [String: Channel]()
func add(channelName: String) -> Channel {
if let channel = self.channels[channelName] {
return channel
} else {
let newChannel = Channel(name: channelName)
self.channels[channelName] = newChannel
return newChannel
}
}
func find(channelName: String) -> Channel? {
return self.channels[channelName]
}
}
So basically when the WebSocket receives some data that is for the given channel, it should check for the event name, and if there is a callback with that event name, call the callback associated to that event name. However, the channel apparently has no callbacks when the handleEvent method is called, even though at the bottom of viewDidLoad it shows as having a callback in the callbacks property for the channel.
Any ideas as to where / why the callback is disappearing?
Update
I've now tried moving the definition of the channel, ch outside of the channelSetup function so it's like this, but with no luck:
class ViewController: UIViewController {
let wSock = wSocket(key: "afa4d38348f89ba9c398")
var ch: Channel = nil
func channelSetup() {
ch = wSock.subscribe("test-channel")
ch.bind("test-event", { (data: JSON) -> Void in
println("I'm the callback getting called")
})
println(ch.callbacks)
}
override func viewDidLoad() {
super.viewDidLoad()
channelSetup()
}
}

Answer 1

I've solved this but not because it was something going on in Swift that I didn't understand. Instead it was just that the way that I had setup the code meant that there were duplicate channel objects being created and the callback was being added to only one of the channels.