Implement perform selector with parameter from a String

Question

I need to implement a perform selector from a String. The Selector must have as parameter a Notification value.

class ChapterViewController: UIViewController {

    var chapterClass:ChapterClass!

    func catchNotificationParagraphFinished(notification:Notification) {

        let name = "catchNotificationParagraphFinished_\(chapter.className!)"
        let selector = NSSelectorFromString(name)

        chapterClass.perform(selector, with: notification)   
    }
}

    class ChapterClass: NSObject {

        func catchNotificationParagraphFinished_Chapter2(notification:Notification) {}
    }

I suppose I'm doing something wrong, because I got this error:

[ISAMGAME.ChapterClass catchNotificationParagraphFinished_Chapter2]: unrecognized selector sent to instance 0x600000052c60

*Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ISAMGAME.ChapterClass catchNotificationParagraphFinished_Chapter2]: unrecognized selector sent to instance 0x600000052c60**

I also tried with:

func catchNotificationParagraphFinished_Chapter2(_ notification:Notification) {}

And also tried using:

let name = "catchNotificationParagraphFinished_\(chapter.className!):"
let selector = Selector((name))

I based my approach thanks to:

genghiskhan · Answer 1 · 2017-07-12T13:07:24.037

0

I believe you have to include the parameter name as well as class name in the selector string, therefore the selector string becomes:

let name = "ChapterClass.catchNotificationParagraphFinished_\(chapter.className!)(notification:)"

edited Jul 12 '17 at 13:07

answered Jul 12 '17 at 12:50

genghiskhan

1,095
12
21

I really need to create my selector from String. Depending of the string, I will call catchNotificationParagraphFinished_Chapter2 or catchNotificationParagraphFinished_Chapter3... etc... I like to avoid to have many "if" conditions. – cmii Jul 12 '17 at 12:58
Same crash "[ISAMGAME.ChapterClass catchNotificationParagraphFinished_Chapter2(notification:)]: unrecognized selector sent to instance" :( – cmii Jul 12 '17 at 13:35
It could be that you can't perform a selector on a class outside of the current class, therefore try calling a method in ChapterClass that is passed a class name and performs the selector on itself – genghiskhan Jul 12 '17 at 13:52
It was a good idea, but I have just tried and the same error appears ... – cmii Jul 12 '17 at 14:07

score 0 · Accepted Answer · answered Jul 12 '17 at 14:49

0

My method works fine, but don't forget to add String type to the constant...

 let name:String = "catchNotificationParagraphFinished_\(chapter.className!):"

answered Jul 12 '17 at 14:49

cmii

3,556
8
38
69

Implement perform selector with parameter from a String

2 Answers2