Clear an optional variable in Swift

var myImage: UIImage?

Is basically short hand for making a UIImage point to nil automatically.

So to reset it back to the original value say:

myImage = nil

Set its value back to nil like this

myImage = nil

Optional is an enum type in Swift; it has two cases:

enum Optional<T> : NilLiteralConvertible {
    case None
    case Some(T)
    ...
}

By assigning an image to your Optional<UIImage>, you have implicitly specified .Some(image). To clear it, you can use .None. But since Optional also conforms to NilLiteralConvertible, you can use the simpler and clearer nil.