It can't read Apple Lossless Audio Codec off of a flash drive, only plays mp3 and wma files that way. Has anyone tried to play ALAC files off of an old ipod or iphone by plugging it into the USB port? Almost my files are ALAC format and it's a pain to convert all of them to mp3s. I could just play them via bluetooth or aux cable off of my android phone, but that reduces sound quality and defeats the whole point of lossless audio. If it works with an apple device, then it may be worth it for me to buy an old ipod classic with a hard drive off of ebay.
I've played music off my iPhone, but no USB jack, just the mini-phono jack. I'm very likely saying something you already know?
I’m a lifelong proponent of uncompressed lossless audio. Try VLC media player, problem could be that VLC might not be able to navigate to the audio files on iOS on play them. With android OSs, I’ve done it that way with USB port successfully with FLAC.
Don't know if you already found out or not, but I'll just answer anyway. I play ALAC from the Music app through USB from an iPhone 6s. After the recent 13 update, though, I haven't been able to skip songs like before (that's probably a different issue than files being ALAC though). Bottom line is, yes you can play ALAC from an iPod/iPhone connected through USB.
UPDATE: I guess the issue is no longer an issue. Don't know what fixed it or when, but it appears to be fixed. Enjoy!
For those who find the thread in the future: the iPod or iPhone is breaking the file out of ALAC format and presenting an uncompressed PCM bitstream to the car over the USB cable. The car stereo doesn't need to know ALAC, it just needs to be ready to accept uncompressed USB audio.