Is it possible to create a fluid UI with interface builder?
For example, say I have a page that has a few fields at the top, some of which are optional. Can I make some of them invisible and have the fields below move up to fill the gap?
Similarly, if I have a tableview in a page followed by a text field, can I have the tableview grow and shrink and still have the text field immediately after it?
The best you can do with interface builder is setting autoresizing masks. So if your view container changes dimensions the iPhone can adjust sizes accordingly.
To answer your questions:
1: You can’t accomplish the functionality directly with interface builder, You can setup your interface but then you’ll have to write the logic in the controller to achieve that functionality.
2: This you can accomplish in interface builder. You add the textField to the footerView of the tableview, and then the text field will always remain at the bottom of the tableView no matter what is displayed in your table.