Some mp3 audio playing in iOS, some not

my app is nearly completed. But there is one big problem left. It has mp3 audio in scenes and quizzes. Now the strange thing is that everything works fine when I test in Safari osx. After exporting to xcode and testing on the iPad and iPhone some audio will not play? Also playing online on iOS gives the same problem. Did anybody run into this and found a solution?

Unfortunately mobile Safari adds another layer of limitations, you can’t run audio triggered in timeline but only for audio triggered with “click” action.

That is exactly what’s happening. Now I know why. Thank you for explaining.