sessionManagerOAuth.swift

let sessionManager: SessionManager = {
    let configuration = URLSessionConfiguration.default
    configuration.httpAdditionalHeaders = SessionManager.defaultHTTPHeaders
    let sessionManager = SessionManager(configuration: configuration)
    let oauthHandler = OAuth2Handler(accessToken: accessToken, refreshToken: refreshToken)
    sessionManager.adapter = oauthHandler
    sessionManager.retrier = oauthHandler
    return sessionManager
}()

var request: DataRequest {
    return sessionManager.request(url, method: method, parameters: parameters, encoding: encoding, headers: headers)
}