If an app on your iPhone stops responding, closes unexpectedly, or won’t open, one of the possible solutions is to force the app to close and reopen the app. This can help clear any temporary issues that may cause the app to malfunction. To force the app to close, you need to swipe up from the bottom of the screen until all running app cards appear, then swipe up on the app card to quit the app. To reopen the app, you need to tap the app icon on the Home Screen or in the App Library. The other options are not recommended as the first steps to troubleshoot an unresponsive app, as they may have unwanted consequences or not address the root cause of the problem.

Deleting the app and redownloading it from the App Store may result in losing data that was stored in the app, and it may not fix the problem if the app is incompatible with your device or software version.

Resetting all settings will erase all your customized settings, such as network, privacy, accessibility, and general preferences, and restore them to the default values. This may not fix the problem if the app is corrupted or has a bug.

Restarting the device may help resolve some minor glitches, but it may not fix the problem if the app is conflicting with another app or service, or if the app needs an update. References:

Apple Device Support Exam Prep Guide, page 9

If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open