The document discusses various user interface (UI) elements that can be used in iPhone application development. It describes UI elements like text fields, buttons, labels, toolbars, navigation bars, tab bars, image views, scroll views, table views, split views, text views, pickers, switches, sliders, alerts and icons. It provides details on how to add each element in code and their important properties. It also gives examples and steps to implement navigation bars, tab bars and split views in an application.