Is it a violation of the iOS Human Interface Guidelines (HIG)—or for that matter, of good UI design—to use pinch and zoom for the user to size elements on the screen, rather than the whole screen/surface itself?

I know that using gestures for the wrong behavior is compliant with the iOS HIG, so I'm trying to make sure I use these gestures correctly.

  • You meant "is not compliant with the iOS HIG", right? – Vitaly Mijiritsky Sep 29 '11 at 9:00

It's ok, as long as the element being resized is clearly marked as selected. If this takes place on a screen where you can zoom in and out, then you need to make sure that the user always knows what will be affected by his actions - the element or the screen. And this can't be done by the location of the fingers alone - you need to provide an explicit selection mechanism.

  • Very cool answer, thanks for talking to the question and thinking about this a bit. – Dan Rosenstark Sep 30 '11 at 2:33
  • Yeah, I've got stuff being selected via a single touch and moveable balls pretty much like IB. I just wanted to (and did) add the pinch-to-zoom option. – Dan Rosenstark Oct 8 '11 at 13:05

Not if the alternate usage is similar to the normal usage of that gesture - resizing an element is conceptually the same as resizing the whole screen, so the user won't have a problem understanding it.

Where you run into issues is if you do something like have the zoom gesture pop up a dialog - technically possible, but there is no conceptual connection to the normal behaviour, so it will confuse the user. Of course, you wouldn't want to design something like that, so that shouldn't be a problem either.


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