I was looking for a way to validate that a string is in fact a URL and I quite liked this piece of code from post (3rd from top) How to check validity of URL in Swift?:
extension String {
var isValidURL: Bool {
let detector = try! NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue)
if let match = detector.firstMatch(in: self, options: [], range: NSRange(location: 0, length: self.utf16.count)) {
// it is a link, if the match covers the whole string
return match.range.length == self.utf16.count
} else {
return false
}
}
}
My first question is: why did this developer choose self.utf16.count and not self.utf8.count or one of its other variations.
My second question is: How do you know this is actually checking that it's a valid URL? Does this meet these requirements? (The documentation for NSDataDetector.link is literally empty. + no comments in apple's code)
A URL is a valid URL if at least one of the following conditions holds:
The URL is a valid URI reference [RFC3986].
The URL is a valid IRI reference and it has no query component. [RFC3987]
The URL is a valid IRI reference and its query component contains no unescaped non-ASCII characters. [RFC3987]
The URL is a valid IRI reference and the character encoding of the URL's Document is UTF-8 or UTF-16. [RFC3987]
A string is a valid non-empty URL if it is a valid URL but it is not the empty string.
A string is a valid URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid URL.
A string is a valid non-empty URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid non-empty URL.
Any comments are appreciated.
