Cook is expected to spend more than two hours making what are likely to be his most extensive public remarks on the App Store, which anchors Apple's $53.8 billion services business.
The maker of "Fortnite," which pits players against in each other in an animated "Battle Royale" fight to the last survivor, is led by CEO Tim Sweeney, who has reveled in the public opportunity to take on Apple.
Industry tracker eMarketer last month said that Spotify has been growing quickly and that its podcasting service is on track to have more listeners in the United States than Apple Podcasts this year.