27.2 Alignment Guides
An alignment guide is used to define a custom position within a view that is to be used when that view is aligned with other views contained in a stack. This allows more complex alignments to be implemented than those offered by the standard alignment types such as center, leading and top, though these standard types may still be used when defining an alignment guide. An alignment guide could, for example, be used to align a view based on a position two thirds along its length or 20 points from the top edge.
Alignment guides are applied to views using the alignmentGuide() modifier which takes as arguments a standard alignment type and a closure which must calculate and return a value indicating the point within the view on which the alignment is to be based. To assist in calculating the alignment position within the view, the closure is passed a ViewDimensions object which can be used to obtain the width and height of the view and also the view’s standard...
