We also need two more nib files, one for each of the two content views we just created. To create these, single-click the Resources folder in the Groups & Files pane so that we create them in the correct place, and then press ␣N or select New File... from the File menu again. This time, when the assistant window comes up, select User Interfaces under the iPhone OS
heading in the left pane .
Select the icon for the View XIB template, which will create a nib with a content view, and then click the Next button. When prompted for a filename, type BlueView.xib. Repeat the steps to create a second nib file called YellowView.xib. Once you’ve done that, you have all the files you need. It’s time to start hooking everything together.