How to Identify Legacy Apps That Might Not Be Compatible With IOS 11
Apple has added several new things in the iOS 10.3 update, and one of them is a tool for identifying 32-bit apps that may be out of date in the next iOS release.
Go to Settings> General> About and scroll down to Apps. If you can press that button, you will be taken to the app compatibility page, which is essentially a graveyard of ancient apps on your phone. If you see any applications here, it means that they have not been updated in 64-bit mode, which was introduced back in 2013. If you cannot click on the apps section, it means that all your apps are up to date.
SensorTower has compiled a list of nearly 200,000 incompatible apps in the App Store, most of which are games or educational apps. If you see an app here that you really care about, or worse, you need it to work, contact the app developer to see if they can update it to 64-bit support.