Three-pane split view interface on iPad landscape mode

Question

iOS Notes and Mail apps have a three-pane split view interface on iPad landscape mode. How can I create such interface? I checked UISplitViewController but it made only two panes (master and detail). Can somebody please enlighten me how to create the leftmost pane?

Answer 1

It's done using custom layout. You have root view controller that loads three other view controllers into three container views. That is all.

Answer 2

Starting iOS 14, you can use UISplitViewController.Style.tripleColumn (UISplitViewControllerStyleTripleColumn in Objective-C) for a three-column layout with a supplementary view: