How can swift closure reference properties of clas

问题:

I have the following 2 controllers listed below. I'm using delegation to try and create a progressWindow which will run code and print it nicely but where the code is arbitrary.

The closures are defined by the class conforming to the protocol (in my case SyncViewController), but I want to change the UI of the progressWindowViewController from SyncViewControllers codeToRun {} closure. How do I do this?

SyncViewController.swift

import UIKit

class SyncViewController: UIViewController, progressWindowDelegate {

    var codeToRun = {
            //(self as! ProgressWindowViewController).theTextView.text = "changed the text"
            print("code to run")
    }
    var codeToCancel = {print("code to cancel")}
    var titleToGive = "Starting Sync..."

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    @IBAction func yesSyncButtonAction(sender: UIButton) {
        //Segue to the ProgressWindowViewController...

    }

    @IBAction func noSyncActionButton(sender: UIButton) {
        tabBarController?.selectedIndex = 1 //assume back to inventory section
    }

    // MARK: - Navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if(segue.identifier == "SyncToProgressSegue"){
            let progressWindow = segue.destinationViewController as! ProgressWindowViewController

            progressWindow.controllerDelegate = self //sets the delegate so we have reference to this window still.

        }
    }

}

ProgressWindowViewController.swift

import UIKit

protocol progressWindowDelegate{
    var titleToGive : String {get}
    var codeToRun : ()->() {get}
    var codeToCancel : ()->() {get}
}


class ProgressWindowViewController: UIViewController {

    @IBOutlet weak var theTextView: UITextView!
    @IBOutlet weak var theProgressBar: UIProgressView!
    @IBOutlet weak var navItemLabel: UINavigationItem!

    //Sets delegate
    var controllerDelegate:progressWindowDelegate!

    override func viewDidLoad() {
        super.viewDidLoad()

        navItemLabel.title! = controllerDelegate.titleToGive

        dispatch_async(dispatch_get_main_queue(),{
            self.controllerDelegate.codeToRun() //Will run code accordingly.
        })

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func cancelNavItemButtonAction(sender: UIBarButtonItem) {
        dispatch_async(dispatch_get_main_queue(),{
            self.controllerDelegate.codeToCancel()
        })
    }

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

An example of how his might be used is downloading thousands of inventory records with images, which would print the inventory details as it grabs them into the progressWindow.

But this progressWindow could also be used for other large/small tasks that need to print particular stuff into the progressWindow textarea (like logging in and therefore coming from a different view controller than sync in my example). The idea is to make it a dynamic class.

回答1:

Instead of creating a variable, just use a function/method?

override func viewDidLoad() {
    super.viewDidLoad()

    dispatch_async(dispatch_get_main_queue(),{
        self.controllerDelegate?.codeToRun(self)
    })
}

.

protocol progressWindowDelegate : class {
    var titleToGive : String {get}
    func codeToRun(progressWindowViewController:ProgressWindowViewController)
    var codeToCancel : ()->() {get}
} 

class SyncViewController: UIViewController, progressWindowDelegate {

func codeToRun(progressWindowViewController:ProgressWindowViewController) {
    print("code to run")
}

Also make delegate weak and optional:

delegate weak var controllerDelegate:progressWindowDelegate? = nil