mp3 Songs won't play on iOS

Yes, SoundEffect is a solution, even if it could be a little bit annoying to change all the songs-dependency in the old code…
Consider that I use songs for background music and sound effects for a lot of other things (noises, voices, etc.) over the background music…
In any case, the reason why the songs won’t play on iOS device (as they play before) remain unresolved…
Any idea?