swift create a method who can return result or throw an error
class SecurityService { static func loginWith(email: String, password: String, callback: (error: NSError?, user: User?) -> Void) -> Void { let URL = ".." let params = [ "email": email, "password": password ] HTTP.request(URL, method: "POST", params: params) { (error, result) in if let error = error { callback(error: error, user: nil) } else { guard let JSON = result else { let someDomain = "some_domain" let someCode = 100 let someInfo = [NSLocalizedDescriptionKey: "No results were sent by the server."] let error = NSError(domain: someDomain, code: someCode, userInfo: someInfo) callback(error: error, user: nil) return } guard let name = JSON["name"] as? String, email = JSON["email"] as? String else { let someDomain = "some_domain" let someCode = 100 let someInfo = [NSLocalizedDescriptionKey: "No user properties were sent by the server."] let error = NSError(domain: someDomain, code: someCode, userInfo: someInfo) callback(error: error, user: nil) return } let user = User(name: name, email: email) callback(error: nil, user: user) } } } }
