UILayoutGuide.md

UILayoutGuide

The UILayoutGuide class is designed to perform all the tasks previously performed by dummy views, but to do it in a safer, more efficient manner. Layout guides do not define a new view. They do not participate in the view hierarchy. Instead, they simply define a rectangular region in their owning view’s coordinate system that can interact with Auto Layout.

Creating Layout Guides

To create a layout guide, you must perform the following steps:

1. Instantiate a new layout guide.
2. Add the layout guide to a view by calling the view’s addLayoutGuide(_:) method.
3. Define the position and size of the layout guide using Auto Layout.

You can use these guides to define the space between elements in your layout. The following example shows layout guides used to define an equal spacing between a series of views.

    let space1 = UILayoutGuide()
    view.addLayoutGuide(space1)

    let space2 = UILayoutGuide()
    view.addLayoutGuide(space2)

    space1.widthAnchor.constraint(equalTo: space2.widthAnchor).isActive = true
    saveButton.trailingAnchor.constraint(equalTo: space1.leadingAnchor).isActive = true
    cancelButton.leadingAnchor.constraint(equalTo: space1.trailingAnchor).isActive = true
    cancelButton.trailingAnchor.constraint(equalTo: space2.leadingAnchor).isActive = true
    clearButton.leadingAnchor.constraint(equalTo: space2.trailingAnchor).isActive = true

Reference: https://developer.apple.com/reference/uikit/uilayoutguide