Swift Functional Programming - Second Edition

The wildcard pattern

The wildcard pattern matches and ignores any value. It consists of an underscore, _. We use a wildcard pattern when we do not care about the values being matched against.

For instance, the following code example ignores the matched values:

for _ in 1...5 {     print("The value in range is ignored") } 

We use _ to ignore the value in the iteration.

The wildcard pattern can be used with optionals as follows:

let anOptionalString: String? = nil switch anOptionalString { case _?: print ("Some") case nil: print ("None") } 

As seen from the preceding example, we matched an optional by _?.

The wildcard pattern can be used to ignore data that we do not need and values that we do not want to match against. The following code example ...