I've had two users contact me over an app update. One of its screens isn't displaying some of its content correctly. Come to find out, they had Apple's Display Zoom setting (under Display & Brightness) set to 'zoomed'. When I had them set back to 'standard', no issues. Both users are using an iPhone "Plus" model as their screenshots came back as 1125 x 2001.
Problem is, I cannot reproduce this at all on my own iPhone 6 Plus or 7 Plus. From looking at the screenshot, most of the UI is scaled a-ok I then have a view to display a math problem. That view's bounds is also correct. However, the view is drawing the wrong graphics assets which now overflow the view's bounds.
For these particular images, I fed Xcode PDF images which under the covers generate standard, @2x and @3x rasterized versions. I used Xcode 8.3.3 to submit the app, so the original PDF data was not included (a feature introduced in Xcode 9). The rest of the UI also makes use of such assets (PDFs dragged in to Xcode). All those images show up a-ok.
Unfortunately, the Simulators do not appear to have any setting to simulate Display Zoom. So I have no idea how to fix the issue, other than having users turn off the Display Zoom feature on their end. Both users have been OK in doing that, but this will cause a burden to those that need that feature enabled.
Anyone have trouble with part of their app not honoring Display Zoom? Any tips/tricks for attempting to reproduce? About the only thing I can think of is if the bounds is somehow a now-integral size? But why would the issue not exist on all "Plus" devices with Display Zoom on? Maybe different OS versions would round differently? Subtle draw bugs?