Regular Expression Check: return boolean and answers - arrays

Question

(Make it short to help others)
check if a string matches to a regex:
text.range(of: regex, options: .regularExpression) == nil
check string selected part matches:
let nsString = self as NSString
let regex = try NSRegularExpression(pattern: pattern)
let allMatches = regex
.matches(in: self, options: [], range: NSRange(location: 0, length: nsString.length))
return allMatches.map { match in
return (1 ..< match.numberOfRanges)
.map { matchIndex in
return nsString.substring(with: match.range(at: matchIndex))
}
}

Answer 1

The first one is easy and we don't actually need NSRegularExpression for that:
extension String {
func hasMatches(_ pattern: String) -> Bool {
return self.range(of: pattern, options: .regularExpression) != nil
}
}
let regex = "(.*) [:] (.*)"
let string = "Tom : how are you?"
print(string.hasMatches(regex))
I would say that we don't even need a utility function for that.
The second is harder to understand, mostly because NSRegularExpression API is not really converted to Swift and it even uses old NSString:
extension String {
func getMatches(_ pattern: String) throws -> [[String]] {
let nsString = self as NSString
let expression = try NSRegularExpression(pattern: pattern)
let matches = expression
.matches(in: self, options: [], range: NSRange(location: 0, length: nsString.length))
return matches.map { match in
let numGroups = match.numberOfRanges
// we are skipping group 0 which contains the pattern itself
return (1 ..< numGroups)
.map { groupIndex in
return nsString.substring(with: match.range(at: groupIndex))
}
}
}
}
print(try! string.getMatches(regex)) // [["Tom", "how are you?"]]
Note that I am returning an array of arrays because the expression can match multiple times.
For example:
let regex = "(\\d+):(\\d+)"
let string = "01:23, 02:34"
print(try! string.getMatches(regex)) // [["01", "23"], ["02", "34"]]