In this case, in PowerApps for iOS, swipe should not close the open PowerApp, you then need to find a way to close a PowerApp. But i strongly support this idea, its a must have.
I love PowerApps but out of interest have looking into Out Systems and I believe their system support swipe actions, as well as force touch I think. This is a must for future developments.
At the very least give the user the option of enabling/disabling the swipe to close function to make use of the swipe in the app. This will open up the ability to swipe left or right on data cards, scroll maps, etc. without the worry of closing the app inadvertently. Personally, when using a mobile device, I only swipe to close to refresh the app after publishing, and hit the home button on the device to close the app.
I recently visited an app that i made a couple months ago that displays records in a list and found myself trying to swipe to delete a record, much like how mail works in ios. This would be a nice to have with the option to have other functinality as well.