O'Reilly logo

Learning iOS Development: A Hands-on Guide to the Fundamentals of iOS Programming by Erica Sadun, Rod Strougo, Maurice Sharp

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

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 ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required