Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_.AppDelegate add:]: unrecognized selector

Question

I created a storyboard called Main.storyboard and created a AddBtnViewController with storyboard ID "addBtnVC". In the App Delegate, I initialized a tab bar with three view controllers programmatically. For one of tab bar view controllers, I created an add button that would transition to the AddBtnViewController programmatically. However, I received this error:

uncaught exception 'NSInvalidArgumentException', reason: '-[_.AppDelegate add:]: unrecognized selector sent to instance 0x7f91cb422a30'

My code:

class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
         //Make add btn for View Controller 1 of Navigation Bar
         let addBtn = UIButton(frame: CGRectMake(0, 0, 30, 30))
         addBtn.addTarget(self, action: #selector(ViewController1.add), forControlEvents: .TouchUpInside)

         let rightBarButton = UIBarButtonItem()
         rightBarButton.customView = addBtn
         NavController.navigationBar.topItem?.rightBarButtonItem = rightBarButton

         return true
    }
}

class ViewController1: UIViewController {
    let addBtnVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("addBtnVC")

    func add(sender: UIButton!) {
        if let addBtnVC = storyboard!.instantiateViewControllerWithIdentifier("addBtnVC") as? AddBtnViewController {
            presentViewController(addBtnVC, animated: true, completion: nil)
        }
    }
}

How do I fix this error?

For posterity:

class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
         let VC1 = UIViewController()

         //Make add btn for View Controller 1 of Navigation Bar
         let addBtn = UIButton(frame: CGRectMake(0, 0, 30, 30))
         addBtn.addTarget(VC1, action: #selector(VC1.add(_:)), forControlEvents: .TouchUpInside)

         let rightBarButton = UIBarButtonItem()
         rightBarButton.customView = addBtn
         NavController.navigationBar.topItem?.rightBarButtonItem = rightBarButton

         return true
    }
}

class ViewController1: UIViewController {
    let addBtnVC:AddButtonViewController = AddButtonViewController()

    func add(sender: UIButton!) {
        let navController = UINavigationController(rootViewController: addBtnVC)
        navController.navigationBar.tintColor = colorPalette.red
        self.presentViewController(navController, animated: true, completion: nil)
    }

}

Also what are you trying to do with this "ViewController1.navigationBar"? You are referencing the class ViewController1, not an object of type ViewController1. Understand the difference, it is very crucial. — Gruntcakes, Aug 29 '16 at 04:20

score 3 · Accepted Answer · answered Aug 29 '16 at 04:16

You set the target of the button action to self which represents the AppDelegate class.

The selector of the button action must be in the same class as the target but it isn't. That's what the error message says. Further the signature of the selector is wrong because it takes one parameter.

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_.AppDelegate add:]: unrecognized selector

1 Answers1