How can I verify that an iOS app has or has not been updated? Today I noticed that an app needed to update. Updates is set to be done automatically, but did not update as it normally would.
When I entered the updates list it just started blinking between the Update- and Open-button, and mostly as Open. After reading the question "Can't update apps in iOS App Store; can only Open" I force quitted the App Store app hoping that could do the trick, hoping the app would appear again with the update. When the App Store restarts the update is gone and has still not appeared in the list after an hour.

The app in question was the Facebook Messenger app. I know by looking at the information in App Store that there were in fact a release of the app today.

How can I verify that the app has or has not been updated?
You can check the version of Messenger installed by going here:

Settings > General > Storage (&amp; iCloud Usage) > Manage Storage > Messenger
Version will be displayed next to app icon.

And you can check the latest version of Messenger in the App Store by going to its page and check the version.

If they are the same, you are good to go. If not, I suggest closing App Store, restarting your iPhone and then checking App Store. It will probably says Update and you can do so.