Thread 1: signal SIGABRT ( Could not cast value of type )

Question

I'm making an iOS app using swift3 on xcode8.

My storyboard is this ( storyboard ).

If I click the button on the third TableViewController from the left, the fourth one will appear. The fourth one is a ViewController to choose library or camera to place a photo onto the imageView on the third TableViewController.

I write the function below in the fourth ViewController's file. The function is a method called when a photo is taken or chosen.

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    let image = info[UIImagePickerControllerOriginalImage] as! UIImage

    if info[UIImagePickerControllerOriginalImage] != nil {

        DispatchQueue.main.async {

            let navigationController = self.presentingViewController as! UINavigationController

            let originVc = navigationController.topViewController as! SettingTableViewController

            originVc.image = image

            self.dismiss(animated: true, completion: nil)
        }

    }

    picker.dismiss(animated: true, completion: nil)
}

func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
    picker.dismiss(animated: true, completion: nil)
}

When this is run, let navigationController = self.presentingViewController as! UINavigationController part is highlighted, and says Thread 1: signal SIGABRT. And also the error Could not cast value of type '[APPNAME].ViewController' to 'UINavigationController' (0x10f85c4a8). is shown(*[APPNAME] is my app name).

Do you know anything about this?

Thank you in advance!

Because your self.presentingViewController is not navigation controller — Prashant Tukadiya, Aug 30 '17 at 12:34
Get rid of the `as!` casts and set a debugger breakpoint that lets you see the **real** object types being assigned. It will tell you where you went wrong more quickly that a question on SO. :) — Phillip Mills, Aug 30 '17 at 12:39
Thanks for comments! Actually, it should be navigation controller because if I make exactlly the same one in another project, it works. However, it doesn't work in my current project. By the way, the third TableViewController's type is SettingTableViewController, so I tried this "let originVc = self.presentingViewController as! SettingTableViewController" instead, but the same error still appears. Any ideas? — Yutaro, Aug 31 '17 at 02:19

Reinier Melian · Answer 1 · 2017-08-30T12:39:02.843

1

This crash is telling you that your presentingViewController is not an UINavigationController, in fact is a UIViewController, so you need to use the .navigationController property and use a if let or guard to avoid any problem

DispatchQueue.main.async {

            if let navigationController = self.presentingViewController.navigationController{

               let originVc = navigationController.topViewController as! SettingTableViewController

               originVc.image = image

               self.dismiss(animated: true, completion: nil)
            }
        }

edited Aug 30 '17 at 12:39

answered Aug 30 '17 at 12:36

Reinier Melian

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Thanks for your answer! If I do that, the codes inside "if let" wasn't run. But as I wrote in the comment of my question now, even "let originVc = self.presentingViewController as! SettingTableViewController" didn't work. – Yutaro Aug 31 '17 at 02:26
check if `self.presentingViewController` is not nil – Reinier Melian Aug 31 '17 at 02:52
I checked it now. It wasn't nil. By the way, the type is "Optional". – Yutaro Aug 31 '17 at 03:34
check if `self.presentingViewController.navigationController` is not nil – Reinier Melian Aug 31 '17 at 03:40
by the way I can see your storyboard image your image server is forbidden for my country ;) – Reinier Melian Aug 31 '17 at 03:50
It was nil. Oh really?! I should use another service then ;) – Yutaro Sep 01 '17 at 11:36
can you post your image in Igmur? @Yutaro – Reinier Melian Sep 01 '17 at 11:45
I added! Thanks for telling me! – Yutaro Sep 01 '17 at 11:50
check your transition type from second to third view controllers must be push type @Yutaro – Reinier Melian Sep 01 '17 at 12:04
check your transition type from second to third view controllers must be push type @Yutaro – Reinier Melian Sep 01 '17 at 12:04
How can I check it? I just connected the top left setting button on the second one with the third one using "show". – Yutaro Sep 01 '17 at 12:28
in the segue created touch and check if segue type is push?? – Reinier Melian Sep 01 '17 at 12:44
check in your viewDidAppear fo your third viewController if self.navigationController is nil – Reinier Melian Sep 01 '17 at 12:57
self.navigationController was nil. – Yutaro Sep 01 '17 at 13:07
Oh, sorry. It wasn't nil ;) – Yutaro Sep 01 '17 at 13:18

Thread 1: signal SIGABRT ( Could not cast value of type )

1 Answers1