Apple issued a how-to guide for users facing the glitch on its support page and pushed an 11.2 iOS update at around 4.30pm. A problem with iOS 11.1.2 means that repeated crashed have been triggered by notifications from 12.15 this morning.
Beginning at midnight, some devices with iOS 11.1.2 installed started rebooting and crashing.
iOS 11.2 seems to have the fix. Apple's security update ended up introducing a problem preventing Mac users from authenticating or connecting to file shares on their Macs. Tap Software Update, and the 11.2 update should be there waiting for you.
Indeed, turning off such notifications was the temporary fix, or setting the clock back to a prior date.
iPhone 5s and later, the iPad mini 2 and later, the iPad Air and later, and the 6th-generation iPod touch are the eligible devices which can be upgraded with this new iOS 11.2. You can also clear these out from this screen. And if one has, then one needs to wait until Apple offers some solution for the bug, until that time there are two options out of which a user can choose one that may be the least tiring.
As noted by software engineer Yoshimasa Niwa, the problem is caused by third-party apps with repeating alerts.
These notifications are most widely used for alerting things the App Store Apps wants an individual to do like feeding one's in-game creatures, or meditation or handling to-dos.
Along with that, other changes in this update include Apple Pay Cash support in the USA, which will let users send and request money from others using Apple Pay. However, you'll need a charger that supports the faster speeds, as well. iMore's Rene Ritchie suggests that Apple Pay Cash will launch early next week, likely when iOS 11.2 was originally slated to be released.
Apart from this, the update fixes all the bugs and other minor issues on the phone.
To close down apps that are running in the background on most iPhones, you double-click the Home Button and then swiping up.