The US Government is asking Apple to open a backdoor in their iPhones to allow the government to snoop on what people are talking about or looking into via their mobile devices. They've actually taken Apple to court on this matter and are insisting they open it up. Apple so far is not complying and refuses to as they see this as an invasion of privacy for their customers.
While I agree with Apple, I can't help but wonder if it also isn't a way of thumbing their noses at Google. First they started with ad blockers, and of course Google's bread and butter is from ads. Now they're making sure they have a closed system, which really can't be said for Google (read: GMAIL).