将照片从照片库导入Xcode中的应用程序

Question

My app keeps crashing and I don't know why. I'm working on a tabbed application part by part and testing it every time I get a part of it done. Right now I'm working on trying to import an image from the user's device but I can't seem to get it.

I'm currently using Xcode 10.2.1 and I understand that there has been some changes to the delegate methods and I have changed them. It succeeds in building but whenever I tap that one particular tab where I would like to import an image, it crashes.

class UserImage: UIViewController,UINavigationControllerDelegate, UIImagePickerControllerDelegate {
    var imagePickerController : UIImagePickerController!

    @IBOutlet var ImageView: UIImageView!

    @IBAction func Edit(_ sender: Any) {
        imagePickerController.delegate = self
        imagePickerController.sourceType = .photoLibrary

        present(imagePickerController, animated: true, completion: nil)
    }

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any])
    {
        if let image = info[.originalImage] as? UIImage { 
            ImageView.image = image
        } else {
            print("Take another")
        }

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

Answer 1

It is crashing because you never actually initialized the UIImagePickerController . Since you marked the imagePickerController as a non optional value, your app is going to crash when you try to reference it but it is still nil . Add this line to the beginning of your Edit function to initialize the variable:

imagePickerController = UIImagePickerController()

Edit: Alternatively, as @rmaddy mentioned, you could just make the controller a local variable of the function. In your example, there is no need to make it a property of the class. Essentially you would just remove the declaration from the top of your class and instead declare it inside the function:

let imagePickerController = UIImagePickerController()