How to do Screenshots using an iPad Air

Unlike recent models of iPhone, iPad and iPadOS do not support the back-tap function to which you lilely refer.

Instead, for recent models of iPad, there is a simple alternative - namely a corner swipe, configured from iPad settings:

Settings > General > Gestures - set Left or Right Corner Swipe to Screenshot

The corner-swipe gesture can be performed with an Apple Pencil - and/or with your finger if Allow Finger to Swipe From Corner is set to ON (as illustrated). When enabled, trigger the screenshot by swiping diagonally from the configured-corner towards the centre of the screen.

You can also trigger screenshots using the established physical button combination/sequence - although the new corner-swipe is significantly more accessible:

Take a screenshot on your iPad - Apple Support

You can also trigger the new QuickNote feature by using a corner-swipe gesture.

See: Take a screenshot on your iPad - Apple Support

1953Moose98Deer1964 Said:

"How to do Screenshots using an iPad Air…. can we set Apple TM to double tap.?!…"

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Looking to Screenshot with Double-Tap?

You cannot create an alternative way. If you have an idea for Apple, then recommend it to them. There may be a third-party app out there form the App Store that allows for this however. Likely, it would be an app for accessibly.

Provide Apple Feedback:

Recommend this as an idea to Apple.  Apple may not get back you, but the more feedback they receive on this, the more they will know what their customers prefer, and what to consider in iOS versions to come.

1. Go Here: Feedback - iPad - Apple
2. Select: "Feature Request" for "Feedback Type"
3. Comment: on why you think this should be an option. Include the URL of this post.
4. Proceed form there as necessary