Even iOS apps occasionally misbehave — they can crash, or freeze, or otherwise stop working. If you’re new to iOS or just haven’t had this happen before, you may not know how to actually quit an app (as opposed to just swiping it off your screen). Here’s how to quit an app and, if you need to, shut down your phone. (We used a phone loaded with a beta of iOS 16, but this will work with earlier versions of the OS just as well.)
Open the App Switcher and swipe sideways to find the app.
While there isn’t any way to close all of your apps at once, you can swipe off up to three apps at a time by using the appropriate number of fingers. Otherwise, if you’ve got a lot of apps running, you’ll have to simply swipe them off one at a time.
If, for any reason, swiping the app off doesn’t solve the problem, then shut down your phone by pressing and holding the side button and either volume button until you see sliders appear. Drag the one that says slide to power off to the right. (If you have an iPhone with a Home button, instead, press and hold the side or the Sleep / Wake button.)
You should then be able to restart it by using the power button.
If worse comes to worst and you can’t shut down your phone this way, you can force restart it. If you have an iPhone 8 or later: