Learning iOS Development: A Hands-on Guide to the Fundamentals of iOS Programming

Constraints

The descriptions in the preceding section are constraints on the relationship between views. Sometimes the relationship is contained in the same view, sometimes between siblings, and sometimes between a view and its container. You can even specify relationships between views in different containers. For instance, you can say that the New Car button is the same width as the Previous button.

Pixels and Points

Before looking at constraints, it is important to understand the difference between pixels and points. Pixels are the physical hardware-addressable elements that show individual elements of color on the screen. They determine the resolution of the screen, and the number of pixels in a given area, or pixel density, determines how ...