Cannot subscript a value of type '[String : An

Question

I'm using Apple's Swift iOS Tutorial. Which is throwing an error,

Cannot subscript a value of type '[String : Any]' with an index of type 'UIImagePickerController.InfoKey'

The function they defined is below.

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

    // The info dictionary may contain multiple representations of the image. You want to use the original.
    guard let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage else {
        fatalError("Expected a dictionary containing an image, but was provided the following: \(info)")
    }

    // Set photoImageView to display the selected image.
    photoImageView.image = selectedImage

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

I'm using Xcode Version 10.0 beta 3, which includes Swift 4.2.

I'd like to understand how to traverse the docs to understand what might have changed or broken.

Answer 1

Method has been changed a little bit in Swift 4.2.

First initialise these two variables:

var imagePicker = UIImagePickerController()
var pickedImageProduct = UIImage()

extension yourViewController: UIImagePickerControllerDelegate,UINavigationControllerDelegate{
//create an IBAction to access Camera
    @IBAction func accessCameraBtn(_ sender: UIButton) {
        imagePicker.delegate = self
        imagePicker.sourceType = UIImagePickerController.SourceType.camera
        self.present(imagePicker, animated: true, completion: nil)
    }
//create an IBAction to access Gallery
    @IBAction func accessGalleryBtn(_ sender: UIButton) {
        imagePicker.delegate = self
        imagePicker.sourceType = UIImagePickerController.SourceType.photoLibrary
        self.present(imagePicker, animated: true, completion: nil)
    }
//Final step put this Delegate    
    func imagePickerController(_ picker: UIImagePickerController,
                               didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

        guard let selectedImage = info[.originalImage] as? UIImage else {
           Print("Error: \(info)")
        }

            pickedImageProduct = selectedImage

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

        dismiss(animated: true, completion: nil)
    }

}

Answer 2

The signature of the method has changed in Swift 4.2

func imagePickerController(_ picker: UIImagePickerController, 
  didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any])

and you have to write

guard let selectedImage = info[.originalImage] as? UIImage else {
    fatalError("Expected a dictionary containing an image, but was provided the following: \(info)")
}

You can figure out such terminology changes yourself by reading the documentation or by commenting out the entire method, retype the first few characters and use code completion.

Answer 3

I'm following also the same tutorial, the updated code looks like this:

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

    // The info dictionary may contain multiple representations of the image. You want to use the original.
    guard let selectedImage = info[.originalImage] as? UIImage else {
        fatalError("Expected a dictionary containing an image, but was provided the following: \(info)")
    }

    // Set photoImageView to display the selected image.
    photoImageView.image = selectedImage

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