How to Update addTarget method to swift 4

Question

when update project code to swift 4 get some error for add.target method how i can fix this error?

 //swift3

var chatLogController: ChatLogController? {
    didSet {
        sendButton.addTarget(chatLogController, action: #selector(ChatLogController.handleSend), for: .touchUpInside)

       uploadImageView.addGestureRecognizer(UITapGestureRecognizer(target: chatLogController, action: #selector(ChatLogController.handleUploadTap)))
    }
}

this error "Argument of '#selector' refers to instance method 'handleSend()' that is not exposed to Objective-C" — Habib Alejalil, Sep 24 '17 at 17:36
Well there's your answer. Just read what the error message says! Put `@objc` in front of your `func handleSend...` (which you didn't even _show_ in your question, for heaven's sake). — matt, Sep 24 '17 at 17:41
No, you use it when you declare it. But, as I said, you didn't show that. Find where you do say `func handleSend` and do what I said to do. — matt, Sep 24 '17 at 18:26

score 9 · Answer 1 · edited Sep 25 '17 at 09:16

9

The hint message is telling you what to do, add @obj before declaring your function.

@objc func handleSend(_ sender: UIGestureRecognizer){
    ...
}

The reason is because:

In Objective-C, a selector is a type that refers to the name of an Objective-C method. In Swift, Objective-C selectors are represented by the Selector structure, and can be constructed using the #selector expression. To create a selector for a method that can be called from Objective-C, pass the name of the method, such as #selector(MyViewController.tappedButton(_:)). To construct a selector for a property’s Objective-C getter or setter method, pass the property name prefixed by the getter: or setter: label, such as #selector(getter: MyViewController.myButton).

Read more here, at Apples documentation.

edited Sep 25 '17 at 09:16

Hamish

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answered Sep 24 '17 at 18:59

Rashwan L

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Great answer for those who just starting coding with Swift. People should answer like this more and more less critic :) – Roi Mulia Sep 24 '17 at 19:10
@RoiMulia, thank you. – Rashwan L Sep 24 '17 at 19:20
@HabibAlejalil, which error and do you use Swift 4? – Rashwan L Sep 26 '17 at 16:04
But when i use objc get new error : "objc can only be used with members of classes, @objc protocols, and concrete extensions of classes" – Habib Alejalil Sep 26 '17 at 16:06
@HabibAlejalil, which Swift version are you running? – Rashwan L Sep 26 '17 at 16:08
after update to swift 4 , get this error "@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes" – Habib Alejalil Sep 26 '17 at 16:08
@RashwanL Swift 4 – Habib Alejalil Sep 26 '17 at 16:10
@RashwanL thanks . but not working on my project when update to swift 4. link : https://github.com/SombreroElGringo/InnKeeper – Habib Alejalil Sep 26 '17 at 16:21
@HabibAlejalil, your project is running fine and the send button works good. Do you run Xcode 9? – Rashwan L Sep 26 '17 at 17:17
@RashwanL i think xcode 9 have bug!! becuase this project work on xcode 8 but after update to swift 4 get error on xcode 9 and i searching more than 2 days and can't fix this error!!! – Habib Alejalil Sep 26 '17 at 19:00
I managed to run the project in Xcode 9 without any problems. Try to clean your project and re-run it. – Rashwan L Sep 26 '17 at 19:02
@RashwanL you update code to swift 4?! – Habib Alejalil Sep 26 '17 at 20:33
No, I did not @HabibAlejalil – Rashwan L Sep 26 '17 at 20:34
When are they gonna replace #selector with a Swift native? – Van Du Tran Nov 09 '17 at 15:54
Any way to implement without @objc function? – Jayprakash Dubey Oct 15 '18 at 13:32
@JayprakashDubey, no not if you´re using the `selector option. – Rashwan L Oct 16 '18 at 06:10

How to Update addTarget method to swift 4

1 Answers1