Thanks for reaching out to the Apple Support Communities! It sounds like you are having issues with your iPhone showing the black screen and dotted circle at times and I am happy to help. If you are seeing this when using specific applications, I recommend checking out this article with steps to follow If an app unexpectedly quits, stops responding, or won’t open .
If you are seeing the message at different times and with different applications, including while using Apple applications, check out this article with the steps for How to back up your iPhone, iPad, and iPod touch . This will give you a couple of options to backup your device before following the steps in this article If your iPhone, iPad, or iPod touch won‘t turn on or is frozen . Specifically, check out these steps:
If your device turns on but gets stuck during start up
If you see the Apple logo or a red or blue screen during startup, try these steps:
- Connect your device to a computer and open iTunes. If you don't have a computer, try to borrow one, or go to an Apple Store or Apple Authorized Service Provider for help.
- While your device is connected, force it to restart.
- On an iPhone X, iPhone 8, or iPhone 8 Plus: Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then, press and hold the Side button until you see the recovery-mode screen.
- On an iPhone 7 or iPhone 7 Plus: Press and hold the Side and Volume Down buttons at the same time. Keep holding them until you see the recovery-mode screen.
- On an iPhone 6s and earlier, iPad, or iPod touch: Press and hold both the Home and the Top (or Side) buttons at the same time. Keep holding them until you see the recovery-mode screen.
- Don't release the buttons when you see the Apple logo. Keep holding until you see the recovery mode screen.
- When you get the option to restore or update, choose Update. iTunes will try to reinstall iOS without erasing your data.
iTunes will download the software for your device. If it takes more than 15 minutes, your device will exit recovery mode and you'll need to repeat steps 2 and 3.
Once you have reinstalled, restore the backup you created and test to see if the issue is still going on. The good news is both articles provide the best steps as well as what to do if you continue to have issues after performing the troubleshooting steps suggested.
Cheers!