used by 'Lessons learned from handling JWT on mobile' article on Medium

token_refresh_snippet_1.swift

typealias Token = String
typealias AuthorizationValue = String

struct UserAuthenticationInfo {
    let bearerToken: Token // the JWT
    let refreshToken: Token
    let expiryDate: Date // computed on creation from 'exp' claim
    var isValid: Bool {
        return expiryDate.compare(Date()) == .orderedDescending
    }
}

protocol TokenRefreshing {
    func refreshAccessToken(_ refreshToken: Token, completion: @escaping (Result<UserAuthenticationInfo, Error>) -> Void)
}

protocol AuthenticationInfoStorage {
    var userAuthenticationInfo: UserAuthenticationInfo?
    func persistUserAuthenticationInfo(_ authenticationInfo: UserAuthenticationInfo?)
    func wipeUserAuthenticationInfo()
}