The Wall Street Journal:

Tim Cook sat down more than a year ago to watch Apple Inc.’s first scripted drama, “Vital Signs," and was troubled by what he saw. The show, a dark, semi-biographical tale of hip hop artist Dr. Dre, featured characters doing lines of cocaine, an extended orgy in a mansion and drawn guns.
It’s too violent, Mr. Cook told Apple Music executive Jimmy Iovine, said people familiar with Apple’s entertainment plans. Apple can’t show this.
…
Apple’s entertainment team must walk a line few in Hollywood would consider. Since Mr. Cook spiked “Vital Signs," Apple has made clear, say producers and agents, that it wants high-quality shows with stars and broad appeal, but it doesn’t want gratuitous sex, profanity or violence.

I know that Apple has always been somewhat puritan in terms of what it allowed in its stores regarding app content, but considering they sell books, movies, and stream albums with explicit content, I can’t say I understand why they’re applying this to their video service…especially when they’re looking to compete against Netflix, a service which practically flaunts its lack of editorial controls.