If the "Zoom in or out" option is unchecked under the "System Preferences" → "Trackpad" → "Scroll & Zoom" window, then the Pinch to resize gesture won't work.
I don't know if you can detect that, but it would be useful to add a note or a help message to let the user know.
If the "Zoom in or out" option is unchecked under the "System Preferences" → "Trackpad" → "Scroll & Zoom" window, then the Pinch to resize gesture won't work.
I don't know if you can detect that, but it would be useful to add a note or a help message to let the user know.