Ios – Cannot subscript a value of type ‘[String : Any]’ with an index of type ‘UIImagePickerController.InfoKey’

iosswiftuiimagepickercontroller

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.

Best Answer

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.

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