Splitting URL fragment into components

URLFragment.swift

extension URL {
    private func splitQuery(_ query: String) -> [String: [String]] {
        return query.components(separatedBy: "&").map { $0.components(separatedBy: "=") }.reduce(into: [String: [String]]()) { result, element in
            guard !element.isEmpty,
                let key = element[0].removingPercentEncoding,
                let value = element.count >= 2 ? element[1].removingPercentEncoding : "" else { return }
            var values = result[key, default: [String]()]
            values.append(value)
            result[key] = values
        }
    }

    var fragmentItems: [String: [String]] {
        guard let fragment = self.fragment else {
            return [:]
        }

        return splitQuery(fragment)
    }

    var queryItems: [String: [String]] {
        guard let query = self.query else {
            return [:]
        }

        return splitQuery(query)
    }
}


// queryItems has the same behavior as fragmentItems

let test = URL(string: "http://example.com#name=Alice%20Barker&name=Bob&job=developer")!
test.fragmentItems // ["name": ["Alice Barker", "Bob"], "job": ["developer"]]
test.fragmentItems["name"] // Optional(["Alice Barker", "Bob"])

let test2 = URL(string: "http://example.com#name")!
test2.fragmentItems // ["name": [""]]
test2.fragmentItems["name"] // Optional([""])

let test3 = URL(string: "http://example.com#")!
test3.fragmentItems // ["": [""]]
test3.fragmentItems["name"] // nil

let test4 = URL(string: "http://example.com")!
test4.fragmentItems // [:]
test4.fragmentItems["name"] // nil