At what point in the ViewController's lifecycle does the information about its View's size become available?

Information about the sizes of the View controller becomes available after the system completes the layout phase, that is, after the lifecycle methods related to positioning and sizing are called.

Specifically, the sizes of the View can be safely used in the following methods:

• viewDidLayoutSubviews() — called after the ViewController has laid out all its subviews, and sizes are already set.
• viewWillAppear(_:) — sizes may not be final yet, so it's better not to rely on them.

Therefore, to get accurate sizes of the View, it is better to use viewDidLayoutSubviews(), where you can obtain the current sizes through the view.frame or view.bounds properties.