XCode: iPhone App step by step

Reference: Create a Hello World app step by step 

In a nutshell:

1. create a new project using Window-based application template (.m, .h and .nib file will be generated automatically)

2. add a view controller class using UIViewController subClass template (.m, .h and .nib file will be generated automatically)

3. add the view controller class to main application Delegate class created in step 1. And initialize it in applicationDidFinishLaunchingWithOption method, set it as the rootViewController as well.

4. edit .xib to add UI Element in View. Make connection (using assistant editor) to element created through Outlet or Action.

5. implement the action in viewController implementation.