On iPhone and iPad if one's designs were reasonably complex, you would have to be involved in writing a lot of
code to support such adaptive layouts. With Auto Layout it makes it easy to support different screen sizes in your apps.
3. Auto Layout
Using Auto Layout, you can create a
dynamic and versatile interface that
responds appropriately to changes in
screen size, device orientation, and
localization.
4. Basic Concept
Expression of the form y = m*x + b,
where:
y and x are attributes of views.
m and b are floating point values.
An attribute is one of left, right, top,
bottom, leading, trailing, width, height,
centerX, centerY, and baseline.