Backstory

In 2024, with foobar2000 mobile v1.6, iOS version requirement was raised due to Xcode 16 supposedly dropping support for building apps for old iOS versions.
Old Android versions were dropped at the same time, making 1.5.x series the long-term-support branch for legacy hardware.

Fast forward to 2026

User request for backport of specific fix prompted me to attempt making a new 1.5.x series build for iOS.
First supposed obstacle was that per Apple's own documentation, old Xcode should be needed to build for iOS 12, as Xcode 26 series has minimum deployment target of iOS 15. This info is outright wrong - Xcode 26.x builds for iOS 12 just fine, though it won't talk to iOS 12 device or run iOS 12 simulator.
First real obstacle was that publishing it required a fake version number - 1.5.x is rejected when appstore distribution channel has 2.25.6. So it was uploaded as 2.25.7 TestFlight beta, with 1.5.4 payload inside. At least it got installed from TestFlight on my own phone (which refuses to speak to new Xcode), all good so far.
Second obstacle was that you can no longer install TestFlight on iOS 12. Apple claims that in such scenarios last supported version is installed - apparently not for Apple's own apps. I still have legitimately installed TestFlight on my own iPhone6+ and it works, but getting beta builds to user's iOS 12 device required sideloading.
Third obstacle was that, in the end, an appstore release should be made - because all other means to publish have some kind of a timebomb attached. I could not determine with enough certainty whether I could publish this without risking users running 2.25.6 getting "upgraded" to 1.5.4 disguised as 2.25.7.

...

So I started investigating how far actual 2.25.x codebase was from running on iOS 12.
The task required somehow getting iOS 12 simulator installed - or getting whole thing to build in Xcode old enough to communicate with my old iPhone.
In the end, Xcode 13 was used, on old Intel macbook, to debug it.
As it turned out, nothing in 2.25.x codebase specifically needs new iOS; only minor changes were needed (mainly related to file/folder picker integration).
foobar2000 mobile v2.25.7 has just been released, with support for iOS 12 restored.

Aftermath

iOS 12 will remain supported for the rest of 2.25.x lifecycle, that is, until the next major release, which is at least several months away.
Bonus: foobar2000 v1.5.4 for iOS wasn't released, but Android build is available for download.

tl;dr

Errors in Apple documentation caused me to unnecessarily cut old iOS users off from foobar2000 updates for the last 2 years.