My Hack around range headers with swifter

swifterRange.swift

import Foundation
import Swifter

public func fileHttpResponseWithRange(r: HttpRequest, data: Data) -> HttpResponse {
    powerRanger:if let rangeHeader = r.headers["range"] {
        let rangeExpression = try! NSRegularExpression(pattern: "bytes=(\\d*)-(\\d*)", options: .caseInsensitive)

        let matches = rangeExpression.matches(in: rangeHeader, options: .anchored, range: NSRange(location: 0, length: rangeHeader.characters.count))
        guard let match = matches.first, match.numberOfRanges == 3 else {
            break powerRanger
        }
        let rangeStartString = (rangeHeader as NSString).substring(with: match.rangeAt(1))
        let rangeEndString = (rangeHeader as NSString).substring(with: match.rangeAt(2))

        guard let rangeStart = Int(rangeStartString), let rangeEnd = Int(rangeEndString) else {
            break powerRanger
        }
        let subData = data.subdata(in: rangeStart..<(rangeEnd + 1))
        let headers = ["Content-Range": "bytes \(rangeStartString)-\(rangeEndString)/\((data.count))"]
        return .raw(206, "OK", headers, { writer in
            try? writer.write(subData)
        })
    }
    return .raw(200, "OK", [:], { writer in
        try? writer.write(data)
    })
}

public func shareFilesFromDirectoryWithRange(_ directoryPath: String, defaults: [String] = ["index.html", "default.html"]) -> ((HttpRequest) -> HttpResponse) {
    return { r in
        guard let fileRelativePath = r.params.first else {
            return .notFound
        }
        if fileRelativePath.value.isEmpty {
            for path in defaults {
                if let file = try? (directoryPath + String.pathSeparator + path).openForReading() {
                    return .raw(200, "OK", [:], { writer in
                        try? writer.write(file)
                        file.close()
                    })
                }
            }
        }
        guard let fileExists = try? (directoryPath + String.pathSeparator + fileRelativePath.value).exists() else {
            return .notFound
        }

        if fileExists {
            guard let fileBody = NSData(contentsOfFile: directoryPath + String.pathSeparator + fileRelativePath.value) else {
                return .internalServerError
            }
            return fileHttpResponseWithRange(r: r, data: fileBody as Data)
        }
        return .notFound
    }
}