I need to adapt to different ios version of the application of, but my iphone is the latest version. How to lower version?
How to lower iOS version
Downgrading iOS devices is not supported. If you need to test on hardware running an older OS version, you have to buy a used device that still has that version installed, and never upgrade it. (You can't choose a specific version to upgrade to either; if you do upgrade, it is always to the latest release version.)
Strange but true.
Thanks for your answer. I just hope it has convenience way for developer.