Bi-Directional communication between ViewController and AppDelegate with swift 2 for iOS

问题

I am developing an iPhone app that uses the PubNub network to publish data to a Raspberry Pi and subscribe to messages from it. Xcode 7, Swift 2. These messages are sent using an object that I call client, which is declared in the AppDelegate.swift init() method. I have been able to successfully reference my AppDelegate from my one and only ViewController, however getting data back to my ViewController from the AppDelegate is where things have gotten tricky for me.

I'm aware that this bi-directional control is probably not ideal. I don't like the concept of both objects knowing about each other. However, since this is for a small DIY home project, for the time being I would like to know how I can get my AppDelegate to directly call a function within the ViewController. All of the suggestions I have found on stack overflow are out of date or do not work. What can I do to easily pass a String to my ViewController from the AppDelegate?

To be more specific: I want to call the setMessage() method of my ViewController from within my client() method at the bottom of AppDelegate, giving the ViewController the string that I receive in the client function.

ViewController

import UIKit

class ViewController: UIViewController {

    var currentMessage = NSString()
    @IBOutlet weak var receivedMessage: UILabel!
    @IBOutlet weak var messageInput: UITextField!
    let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    @IBAction func sendButtonPressed(sender: AnyObject) {
        let messageToSend = messageInput.text
        appDelegate.client.publish(messageToSend, toChannel: "my_channel", compressed: false, withCompletion: nil)
    }

    func setMessage(message : String) {
        receivedMessage.text = message
    }
}

AppDelegate

import UIKit
import PubNub

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate, PNObjectEventListener {

    var client : PubNub
    var config : PNConfiguration

    override init() {
        config = PNConfiguration(publishKey: "pub-c-ecaea738-6b0f-4c8d-80a9-a684e405dbe9",
                                 subscribeKey: "sub-c-b71a16f8-5056-11e5-81b5-02ee2ddab7fe")

        client = PubNub.clientWithConfiguration(config)
        client.subscribeToChannels(["my_channel"], withPresence: false)

        super.init()
        client.addListener(self)
    }

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        return true
    }

    func applicationWillTerminate(application: UIApplication) {
        client.unsubscribeFromAll()
    }

    func client(client: PubNub!, didReceiveMessage message: PNMessageResult!) {
        let messageString = String(message.data.message);
        print(messageString)
    }
}

回答1:

From your AppDelegate you can use

let vc=self.window!.rootViewController as! ViewController

vc.setMessage(someText)

but, I would use an NSNotification and have the view controller subscribe to that.

来源：https://stackoverflow.com/questions/35593574/bi-directional-communication-between-viewcontroller-and-appdelegate-with-swift-2

标签

ios

iphone

swift

uiviewcontroller

appdelegate