Best way of using web services on iOS?

I'd like to build an iOS app which lets you log in to a web service.

After that, the app would (when the user chooses) send the login name/pass, together with the requested variable(s), over https. For instance开发者_JAVA百科 after requesting 'news-update', it would receive the requested info in XML format... something like:

<news-update>
  <title>Kim Jong-un Promoted</title>
  <story>North Korean leader Kim Jong-il's youngest son, Kim Jong-un, has been appointed a general, amid rumours he is being anointed as successor...</story>
</news-update>

What APIs and techniques should I use for these kind of tasks? I don't want to use any UIWebViews, but instead use standard UI elements.

What @Ole said, except instead use ASIHTTPRequest to send and receive data over the network.

NSURLConnection to send and receive data over the network and NSXMLParser to parse it.

RestKit provides excellent support for quick and easy RESTful requests: http://restkit.org/