iOS does not allow sounds to be played unless you start playing them as a result of user interaction. So you could do something like:
var audiosource = this.entity.audiosource;
var startSound = function () {
document.removeEventListener('click', startSound);
audiosource.play('mysound');
}
var isIOS = /iPad|iPhone|iPod/.test(navigator.platform);
if (isIOS)
document.addEventListener('click', startSound);