Initializer

init(string:relativeTo:)

iOS 8.0+ iPadOS 8.0+ Mac Catalyst 8.0+ macOS 10.10+ tvOS 9.0+ watchOS 2.0+

Creates a URL instance from the provided string, relative to another URL.

init?(string: String, relativeTo url: URL?)

Parameters

string: A relative URL location.
url: A URL that provides a base location that the string extends.

Discussion

Important

For apps linked on or after iOS 17 and aligned OS versions, URL parsing has updated from the obsolete RFC 1738/1808 parsing to the same RFC 3986 parsing as URLComponents. This unifies the parsing behaviors of the URL and URLComponents APIs. Now, URL automatically percent- and IDNA-encodes invalid characters to help create a valid URL.

This initializer returns nil if the string doesn’t represent a valid URL even after encoding invalid characters. To check if a URL string is strictly valid according to the RFC, use the new init(string:encodingInvalidCharacters:) initializer and pass encodingInvalidCharacters: false. This leaves all characters as they are and returns nil if the URL string is explicitly invalid.