Inside iOS 11: Early FLAC audio playback comes to iOS via new Files app
An unexpected feature of Apple's first iOS 11 developer beta is rudimentary support for FLAC audio playback, which may hint at broader compatibility coming in the final release.

The option currently appears limited to the Files app for iPhone and iPad. That may presage eventual support in the Music app, as well as in iTunes on desktops, which would be needed to automatically sync files. Apple doesn't use FLAC on Apple Music or the iTunes Store.

FLAC is a lossless audio format, maximizing quality at the expense of storage and bandwidth. iOS and iTunes do support Apple Lossless, but while the format offers a smaller footprint, it isn't as commonplace.
Some other iOS 11 enhancements include an overhauled Control Center, person-to-person Apple Pay transfers, and iPad-oriented upgrades like drag-and-drop, a Mac-style dock, and simpler multitasking.
A public beta of iOS 11 should be available later this month. The finished software is due this fall, most likely ahead of new iPhones.

The option currently appears limited to the Files app for iPhone and iPad. That may presage eventual support in the Music app, as well as in iTunes on desktops, which would be needed to automatically sync files. Apple doesn't use FLAC on Apple Music or the iTunes Store.

FLAC is a lossless audio format, maximizing quality at the expense of storage and bandwidth. iOS and iTunes do support Apple Lossless, but while the format offers a smaller footprint, it isn't as commonplace.
Some other iOS 11 enhancements include an overhauled Control Center, person-to-person Apple Pay transfers, and iPad-oriented upgrades like drag-and-drop, a Mac-style dock, and simpler multitasking.
A public beta of iOS 11 should be available later this month. The finished software is due this fall, most likely ahead of new iPhones.

Comments
If it comes to the Music app...well then I'll finally be able to stop using shitty 3rd party apps like Vox to play my FLAC files. I hate using 2 separate Music apps.
2) If you really want lossless then why not ALAC? As Melgross states, it’s better.
Yes, I was wondering what the advantage of FLAC over ALAC was, given native support for ALAC on iTunes/ Apple Music.
I guess the only thing you avoid by being able to play FLAC files directly is converting it to another format. I am an avid collector of concerts and (ahem!) rarities and most of these are traded as FLAC files (or the older, now hardly used, SHN files).
Sites like HDTracks give you the option of downloading as AIFF, Wave, ALAC or FLAC, so I don't see that much of an advantage in having native FLAC support. It will definitely be a minor convenience, but nothing lost if it is not there.
It is nice to hear that Apple is adopting FLAC support.
People with HD lossless music collections tend (to date) to use stuff from other vendors, both hardware and software, so it's not such a big leap.
apple's Core Audio was meant for audio professionals, who prefer a fixed output. In other words, you set whether the machine will output 16.44.1 or 24/96, and everything will output at those specs. The problem is that for random playback, it converts everything, if necessary, to whatever the settings are. So if you've got a 24/96 file, but the computer is set for 16/44.1, it will convert to that before playing the file (the original file remains untouched).
Apple needs to do two things. First upgrade to 24/192 D/As, they're pretty cheap these days, even good ones, and allow a freesync for output. Both would eliminate most of the "iTunes sounds bad" cries I get.
so there's no reason why Apple can't do this, and for very little more than they're spending now. I know a fair number of people who would switch to Apple's devices if they did that.