URLCredentialHelper.swift

public struct URLCredentialHelper {
    enum URLCredentialError {
        static let invalidUrl = NSError(domain: NSURLErrorDomain, code: NSURLErrorBadURL, userInfo: nil)
    }

    static func store(user: String, password: String, url: String) throws {
        let protectionSpace = try createProtectionSpace(for: url)
        let credentital = URLCredential(user: user, password: password, persistence: .permanent)
        URLCredentialStorage.shared.set(credentital, for: protectionSpace)
    }

    static func getPassword(of user: String, at url: String) throws -> String? {
        let protectionSpace = try createProtectionSpace(for: url)
        let credentitals = URLCredentialStorage.shared.credentials(for: protectionSpace)
        return credentitals?[user]?.password
    }

    static func deleteCredential(of user: String, at url: String) throws {
        let protectionSpace = try createProtectionSpace(for: url)
        let credentitals = URLCredentialStorage.shared.credentials(for: protectionSpace)
        guard let credentialOfUser = credentitals?[user] else {
            return
        }
        URLCredentialStorage.shared.remove(credentialOfUser, for: protectionSpace)
    }

    private static func createProtectionSpace(for urlString: String) throws -> URLProtectionSpace {
        guard let url = URL(string: urlString), let host = url.host else {
            throw URLCredentialError.invalidUrl
        }
        return URLProtectionSpace(
            host: host,
            port: url.port ?? 80,
            protocol: url.scheme,
            realm: nil,
            authenticationMethod: NSURLAuthenticationMethodHTTPDigest
        )
    }
}