Once you’ve created an optional, you’ll want to be able to access the value inside. However, if you just try to use the optional, you will get a compile-time error:

var a = 4
var b: Int? = 3
let sum = a + b // ERROR: Value of optional type 'Int?' must be unwrapped to a value of type 'Int'

The easiest way to wrap an optional is using the ! operator. This process is called force unwrapping and will break open the optional and let you use the underlying value:

var a = 4
var b: Int? = 3
let sum = a + b!
print(sum) // Prints 7

But be careful! If the underlying value is nil, your program will crash:

var a = 4
var b: Int? = nil
let sum = a + b! // Fatal error: Unexpectedly found nil while unwrapping an Optional value
print(sum)

Make sure to only use the ! operator if you are absolutely sure that the value isn’t nil. To be safe, you can check using an if statement:

var a = 4
var b: Int? = nil
if b != nil {
    let sum = a + b!
    print(sum) Prints 7
}