Extract regex matches

demo.swift

extension String {
	func matchingStrings(regex: String) -> [[String]] {
		guard let regex = try? NSRegularExpression(pattern: regex, options: []) else { return [] }
		let nsString = self as NSString
		let results  = regex.matches(in: self, options: [], range: NSMakeRange(0, nsString.length))
		return results.map { result in
			(0..<result.numberOfRanges).map { result.rangeAt($0).location != NSNotFound
				? nsString.substring(with: result.rangeAt($0))
				: ""
			}
		}
	}
}


class MatchingStringTests: XCTestCase {
	func test1() {
		let actual = "prefix12 aaa3 prefix45".matchingStrings(regex: "fix([0-9])([0-9])").description
		let expected = [["fix12", "1", "2"], ["fix45", "4", "5"]].description
		XCTAssertEqual(actual, expected)
	}

	func test2() {
		let actual = "prefix12".matchingStrings(regex: "(?:prefix)?([0-9]+)").description
		let expected = [["prefix12", "12"]].description
		XCTAssertEqual(actual, expected)
	}
	
	func test3() {
		let actual = "12".matchingStrings(regex: "(?:prefix)?([0-9]+)").description
		let expected = [["12", "12"]].description
		XCTAssertEqual(actual, expected)
	}
	
	func test4() {
		let actual = "prefix12suffix".matchingStrings(regex: "fix([0-9]+)su").first?[1].description
		let expected = "12".description
		XCTAssertEqual(actual, expected)
	}
}