What does an exclamation mark mean in the Swift language?

In this tutorial, we will see what an exclamation mark means in Swift. And we will also see the purpose of using exclamation mark with an example.

In the Swift programming language, an exclamation mark (!) is used to indicate that something is optional. This means that the value of the item may be nil, or absent, at runtime.

For example, consider the following code snippet:

let name: String? = "John"

if name != nil {
    print("Hello, \(name!)")

In this code, the name variable is declared as an optional String, indicated by the ? after the type declaration. This means that the name variable can hold a String value, or it can be nil.

In the if statement, the name variable is checked to see if it is not nil. If it is not nil, the exclamation mark is used to force-unwrap the optional value and access the underlying String value.

It’s important to note that using the exclamation mark to force-unwrap an optional can be dangerous if the optional is nil, as it will result in a runtime error. It’s generally recommended to use optional binding or the nil-coalescing operator (??) to safely handle optional values.

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