One of the general principles of user interface design should be that when a user has to choose an option, it should be easily reversible – and it should be obvious how to do so.
Take a look at this grab, from Apple’s Keynote on iOS.
When I tapped on the button to insert an image, the iPad gave me the standard privacy control asking if I wanted to grant Keynote access to my photos. I accidentally hit “no”.
Now, whenever I open up the Photos control, I don’t see any images – but I do see an explanation of why I don’t see anything, and instructions on how to change that option if I wish.
That’s good design. It’s reversible, and it tells me how.
