Описание тега uigraphicscontext
The UIGraphicsContext is not a class as you might think, but a set of functions that allows access to functions of CGContext. UIGraphicsContext is often used to create images or PDFs from code.
The UIGraphicsContext is the programmatic interface to the graphics contexts.
Since iOS 10 and tvOS 10 UIGraphicsRenderer and its subclasses facilitates the creation of documents via UIGraphicsRendererContext, which are based on Objective-C / Swift classes. The creation process is quite similar to working with functions from UIGraphicsContext so that these functions become less and less important.