title: How to grey out a button to let the user know that it is currently disabled in iOS?
body: <p>I'm currently developing a simple iOS app using Xcode and Swift. In my app, there is a button that some times is disabled/enabled, depending on something else the user have touched. But when I set "button.enabled = false", I also what the button to grey out, so that the user knows the button is currently disabled. How could this be done?</p>