How to create popover menus using UIPopoverPresentationController

Swift version: 5.6

Paul Hudson @twostraws May 28th 2019

Show a UIAlertController action sheet on iPad isn't as easy as on iPhone. The reason for this is simple: on iPhone the action sheet slides up from the bottom, effectively owning the user's attention until it's dismissed, whereas on iPad it could be shown from anywhere. In fact, if you just try and show one on an iPad like this, your app crashes:

let ac = UIAlertController(title: "Hello!", message: "This is a test.", preferredStyle: .actionSheet)
present(ac, animated: true)

The solution is to use a UIPopoverPresentationController, which gets created for you when you try to access the popoverPresentationController property of a UIAlertController. With this, you can tell it where to show from (and what view those coordinates relate to) before presenting the action sheet, which makes it work correctly on iPad.

To rewrite the previous lines so they work, you'd do this:

let popover = ac.popoverPresentationController
popover?.sourceView = view
popover?.sourceRect = CGRect(x: 32, y: 32, width: 64, height: 64)

present(ac, animated: true)