Описание тега pure-layout
The ultimate API for iOS & OS X Auto Layout — impressively simple, immensely powerful. PureLayout extends UIView/NSView, NSArray, and NSLayoutConstraint with a comprehensive Auto Layout API that is modeled after Apple's own frameworks.
PureLayout is a cross-platform Objective-C library that works (and looks!) great in Swift. It is fully backwards-compatible with all versions of iOS and OS X that support Auto Layout.
PureLayout provides a fully capable and developer-friendly interface for Auto Layout. It is designed for clarity and simplicity, and takes inspiration from the AutoLayout UI options available in Interface Builder while delivering far more flexibility. The API is also highly efficient, as it adds only a thin layer of third party code and is engineered for maximum performance.