From Xojo Documentation
| This item was deprecated in version 2020r2.
Please use MobileMessageBox as a replacement.
| This class is supported on Mobile (iOS).
Use ＃If...＃Endif with the Target... constants to ensure you only use this class where it is supported.
New in 2016r2
Used to asynchronously display alerts.
Since iOSMessageBox is asynchronous, any code after the Show method is executed after the message box is displayed. Use the ButtonAction event handler to get the results of a button selection and to run code based on the selection. Here are Apple's UI guidelines for the text and buttons in a MessageBox: