Ask HN: List of “must do's” before launching iOS app

I am new to the world of iOS dev and throwing together a small app as a side project. I have found a few articles about launching apps that are mostly geared around gaining hype, PR, etc.

I am looking for advice about "must do" tasks, from a technical standpoint, before releasing an app. Examples may be "include library XYZ to collect metrics", "incorporate analytics XYZ".

What are items you would regret forgetting to do before submiting your app for approval?