The mysteries of "Nil Coalescing Operator" in Swift

What is this madness?

As a one-liner:

Easy unwrapping of optionals in one line.

Example:

For the sake of this example, the optional is of Int? type, but of course it works for every type, just make sure that the fallback you’re providing is type correct.

optionalValue is an optional, if it’s nil I want to assign a default value to it. If it’s not it can keep its own value.

Let’s define a new constant called value to hold the result and call the “Nil Coalescing Operator” which is ?? to unwrap the optional and if necessary to provide a default value for it.

let value = optionalValue ?? 0

Nothing more. If optionalValue has a value it’ll be:

value = optionalValue

If optionalValue is nil than:

value = 0

More Infos