Tag: multithreading

How to Respond to an Authentication Challenge | iOS

How to Respond to an Authentication Challenge

If a session requires authentication it creates authentication challenge

 URLSession:task:didReceiveChallenge:completionHandler: 

in order for the connection to continue, the delegate has three options.

  • Provide authentication credentials
  • Attempt to continue without credentails
  • Cancel the authentication request.

NSURLProtectionSpace will give all information about the authentication type and failure if any attempts failed earlier.

Providing Credentials

To attempt to authenticate, the application should create an NSURLCredential object with authentication information of the form expected by the server. You can determine the server’s authentication method by calling authenticationMethod on the protection space.

  • HTTP basic authentication (NSURLAuthenticationMethodHTTPBasic) requires a user name and password. P
  • HTTP digest authentication (NSURLAuthenticationMethodHTTPDigest), like basic authentication, requires a user name and password.withcredentialWithUser:password:persistence:.
  • Client certificate authentication (NSURLAuthenticationMethodClientCertificate) requires the system identity and all certificates needed to authenticate with the server. Create an NSURLCredential object.
  • Server trust authentication (NSURLAuthenticationMethodServerTrust) requires a trust provided by the protection space of the authentication challenge.

Continuing Without Credentials

If the delegate chooses not to provide a credential for the authentication challenge, it can attempt to continue without one.

• NSURLSessionAuthChallengePerformDefaultHandling processes the request as though the delegate did not provide a delegate method to handle the challenge.

  • NSURLSessionAuthChallengeRejectProtectionSpace rejects the challenge. Depending on the authentication types allowed by the server’s response, the URL loading class may call this delegate method more than once, for additional protection spaces.

Canceling the Connection

The delegate may also choose to cancel the authentication challenge, by passing NSURLSessionAuthChallengeCancelAuthenticationChallenge to the provided completion handler block.

iOS Concurrency | Introduction | Options

Concurrency is two sided-weapon, that you should master and learn how to use because it will help you to write efficient code with fast execution but if you are misusing it, then results will be poor app performance, crashes etc.

So before writing code think about the problem, why do we need that and which API do you need to resolve it.

In iOS, we have different APIs that we can be used. But wait here the question is why do we need Concurrency?

  • Utilize iOS Hardware: Now all of the iOS devices are with multi-core processors that allow developers to execute multiple tasks parallel. So here we can earn lots of benefits.
  • Better User Experience: Code for call multiple web services, handle IO and some heavy tasks etc will freeze UI and make your app nonresponsive so if as a user I face this I will close the app for sure, but with concurrency, all tasks can be done in the background without hanging the main thread.
  • APIs like NSOperation and Dispatch Queues makes it really easy: Earlier creating and managing threads is not easy that’s the reason everyone gets scared when they hear about concurrency. Another major advantage of APIs is, it will also help you to manage synchronization to avoid the race condition, it happens with two threads try to access the shared resource.