Protocol Method Is Not Calling

Question

I am trying to use protocols with swift. I don't know why it is not working.

Second View controller:

protocol passBackTheVoice {
    func sendVoiceMessage(name: String)
}

class VoiceRecordViewController: UIViewController {
    var passBackDelegate: passBackTheVoice?
    ….
    ….

    func uploadCompleted() {
            self.passBackDelegate?.sendVoiceMessage(voiceName)
        self.dismissViewControllerAnimated(true, completion: nil)
    }
}

First View Controller:

class ChatViewController: UIViewController, passBackTheVoice {
    var voiceRecordVC = VoiceRecordViewController()

    override func viewDidLoad() {
        voiceRecordVC.passBackDelegate=self
    }

    func sendVoiceMessage(name: String) {
        print("chat view \(name)")
    }
}

My sendVoiceMessage method is not calling. Where is the problem and how can i solve?

Ps: Don't know this is related but, firstly my ChatViewController is showing then user touches to a button i am showing VoiceRecordViewController to user. Then user creating a voice file and i want to pass back this file to my ChatViewController.

`VoiceRecordViewController()` creates a brand new instance of the controller. It's **not** the controller instance in the storyboard. — vadian, Jan 28 '17 at 22:04
Did you attempt some debugging? Does `uploadCompleted()` ever get called? If so, is `passBackDelegate` `nil` inside it? — Hamish, Jan 28 '17 at 22:05
I debugged and i am sure uploadCompleted is calling. But when i check this line : self.passBackDelegate?.sendVoiceMessage(voiceName) passBackDelegate is looking nil. I guess this is the problem. How to resolve? — Tolgay Toklar, Jan 28 '17 at 22:06
it is Swift convention to name your protocols starting with an uppercase letter — Leo Dabus, Jan 28 '17 at 22:18
See vadian's point. You are setting the `delegate` of `VoiceRecordViewController` that you instantiate here, rather than the one that is instantiated when you segue to it. Instead, have a `prepareForSegue` that sets it. See http://stackoverflow.com/a/9736559/1271826. — Rob, Jan 28 '17 at 22:19
What happens if i use sharedInstance instead of creating a new instance? — Tolgay Toklar, Jan 28 '17 at 22:24
how do you present `VoiceRecordViewController`? from code? or via segue from storyboard? — André Slotta, Jan 28 '17 at 22:28
Then set `passBackDelegate` of that `sharedInstance`. (You obviously lose the ability to use storyboard segues at that point.) But you're obviously not transitioning to the `voiceRecordVC` that you instantiated here because your `passBackDelegate` is `nil`. By the way, if you're really using a shared instance of that `VoiceRecordViewController`, then you should (a) make your protocol a `class` protocol; and (b) define `passBackDelegate` to be `weak`. You can only get away with sloppiness of not using weak delegates if you know that the presented VC will be released before the parent VC. — Rob, Jan 28 '17 at 22:31

Mücahit Tekin · Accepted Answer · 2017-01-29T12:35:17.123

Firstly if you present your view controller from segue you have to use this code:

class ChatViewController: UIViewController, passBackTheVoice {


        override func viewDidLoad() {

        }

        func sendVoiceMessage(name: String) {
            print("chat view \(name)")
        }

        override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

            if segue.identifier == "YOUR_IDENTIFIER_IN_STORYBOARD" {
                let vc = segue.destination as! VoiceRecordViewController
                vc.delegate = self
            }

        }


    }

If you present manually use this code:

class ChatViewController: UIViewController, passBackTheVoice {

        override func viewDidLoad() {


        }

        func sendVoiceMessage(name: String) {
            print("chat view \(name)")
        }

        func goTovoiceRecordVC(){
            let voiceRecordVC = VoiceRecordViewController() // load from storyboard or nib whatever you want
            voiceRecordVC.passBackDelegate=self
            present(voiceRecordVC, animated: true, completion: nil)
        }

    }

Protocol Method Is Not Calling

1 Answers1