Never Keyword in Swift

The Never keyword is a special return type in Swift. When this function call occurs, it tells the compiler that exec will never return

According to Apple:-

“The return type of functions that do not return normally, that is, a type with no values.”

Never keyword used by fatalError() and preconditionFailure() functions.

We can use it as a return type when declaring a method, closure, or function that unconditionally throws an error, traps, or otherwise does not terminate.

func method1() -> Never {

    fatalError("Something very, very bad happened")

}

• Never allows a function or method to be thrown: e.g. () throws -> never. Throwing allows a secondary path for error handling, even in functions that were not expected to return.
• As a first-class type, NEVER works with generics in a way that the @noreturn attribute cannot.
• Never actively prevents a function from claiming both a return type and no-return at the same time.

The first note (with regard to secondary error treatment) is perhaps particularly important. A function can never have complex arguments and throws – not necessarily crashes.

Let’s look at some interesting use cases and compare between never and void

Comparision between NEVER and VOID return type :

VOID:

That’s all for this article.

We hope you liked the article.

Please visit my other blogs here.