ChatGPT official iOS app (US only) is now live! 
This official app is free (no ads!), syncs your history across devices, and brings you the newest model improvements from OpenAI.
Rolling out in other countries over upcoming weeks, via @Greg Brockman
Where does one file a problem report for the official mobile app? I found that the official iOS mobile app is currently not compatible with large text settings on the iPhone. When a large text setting is used, the continue button does not get displayed at the bottom of the very first message screen displayed after login. A user has no way of getting past the screen without first reducing the text size setting. This occurred with my iPhone 13 mini, iOS 16.4.1.
help.openai.com, click the circle icon in lower right and you can submit a message to support team.