Picker Error Message on Exit (encountered while discovering extensions: Error Domain=PlugInKit Code=13) With Swift 4 - Xcode 9

Question

Similar to

PhotoPicker discovery error: Error Domain=PlugInKit Code=13

and also to

https://forums.developer.apple.com/thread/82105

BUT I have t

Answer 1

Make sure you declare that your class implements UINavigationControllerDelegate.

extension MyViewController: UINavigationControllerDelegate {}

For some reason in Xcode 9.0 it warned me to declare the delegate as such:

imagePicker.delegate = self as? UIImagePickerControllerDelegate & UINavigationControllerDelegate