SwiftLogin.swift

@discardableResult func login(_ email: String, _ password: String, onSuccess: @escaping () -> Void, onFailure: @escaping (String) -> Void) -> Request {
    let request = service.resource("/login")
        .request(.post, json: ["email": email, "password": password])
        .onSuccess { entity in
            guard let json: [String: String] = entity.typedContent() else {
                onFailure("JSON parsing error")
                return
            }

            guard let token = json["jwt"] else {
                onFailure("JWT token missing")
                return
            }

            self.authToken = token
            onSuccess()
        }
        .onFailure { (error) in
            onFailure(error.userMessage)
    }

    return request
}