Advanced interfaces rely on stacked combinations of simple UIView subclasses (buttons, labels, images, etc) combined with images and animations, and no more.
Generally, the process begins by receiving wireframes from a designer. If you are making the app yourself, you'll obviously have to design it yourself. The constitution of a wireframe depends on the designer in question, but are commonly photoshop files that fully realize the interface as images.
As a developer, your job is to cut out those images, import them into your project, and layer them appropriately to match the given wireframes.
Very complex interfaces may seem daunting, but always lean on layered images ultimately.