In this guide
You cannot own every iPhone, and you do not need to. A short set chosen by method covers most of the risk. This page gives you the method instead of a model list, because lists go out of date within a year.
What actually differs between iPhones
Look for differences that change how your app looks or behaves:
- Screen size. A small screen breaks layouts that a large one hides: clipped text, buttons off screen, keyboards covering fields.
- Screen shape. Notch, Dynamic Island-style cutouts and the older home-button design change the safe areas at the top and bottom. Content that ignores safe areas is cut off or overlapped.
- Performance and memory. An older phone shows slow screens, long launch times and memory warnings.
- iOS version. The newest phone usually runs the newest iOS; an old one often cannot. See which iOS versions to support.
- Hardware features. Face ID versus a fingerprint button, camera setup, haptics.
The selection method
- List what you own. Write down model, iOS version and screen size.
- Find your gaps. Compare with the five differences above.
- Pick for gaps, not for the newest. Aim for: - one small screen device, - one large screen device, - one older device that still runs the oldest iOS you support, - and one with the newest iOS, which is probably yours. One phone can fill several of these roles. Two or three phones usually cover the list.
- Check Apple's official specs for any model you consider buying (screen size, supported iOS version) instead of relying on third-party lists.
Use the simulator for the rest
The simulator is good for extra screen sizes and dark mode checks. It is weak on real performance, battery, camera and push behavior. Use the simulator to widen coverage and real devices to confirm. See also dark mode testing.
Let testers fill the remaining gaps
Ask every tester for their iPhone model and iOS version in the feedback. After a round, tally which models appeared. That tells you which devices your real early users have, and which gaps to close next. See plan TestFlight groups for how to reach different testers.
A simple device sheet
| Role | Have it? | Notes |
|---|---|---|
| Small screen | ||
| Large screen | ||
| Oldest supported iOS | ||
| Newest iOS | ||
| Notch / cutout |
Fill in the table once, re-check yearly.
Do not
- Buy a phone just because it is new.
- Test only on the phone you use daily; you know its quirks too well.
- Skip the old device; performance problems often show up there first.
The Android equivalent is covered in which Android devices to test on. Hub: iOS app testing. Related: which iOS versions to support.
See how AppReviewX works: private, structured feedback from other developers on their own phones.