init(_:as:)

Declaration

init(_ pattern: String, as outputType: Output.Type = Output.self) throws

Parameters

• pattern:

  A string with regular expression syntax.

• outputType:

  The desired type for the output captures.

Discussion

You can use this initializer to create a Regex instance from a regular expression that you have stored in pattern when you know the capture structure of the regular expression in advance.

In this example, the regular expression includes two parenthesized capture groups, so the capture type is (Substring, Substring, Substring). The first substring in the tuple represents the entire match, while the second and third substrings represent the first and second capture group, respectively.

let keyAndValue = try Regex("(.+): (.+)", as: (Substring, Substring, Substring).self)

This initializer throws an error if pattern uses invalid regular expression syntax, or if outputType does not match the capture structure declared by pattern. If you don’t know the capture structure in advance, use the init(_:) initializer instead.