Following the publication of Apple's absolutely stellar iOS Security white paper in February, Steve Gibson of the TWiT network's Security Now! show spent three episodes going through it, providing extra explanation and context. Gibson was incredibly impressed by the iOS Security white paper, and by Apple's security implementation in general, calling it "amazing" many times over, especially the Apple A7 and its secure enclave. he also widely praised Apple's choices for the crypto they implemented, and especially how user- and privacy-focused their choices were.
Gibson did point out the iCloud Keychain cryptography wasn't as good as the rest of the system, and that things like iMessage chose convenience for users over absolute security at some points. While Apple's close approach is irksome to some, Gibson notes it's also why there's virtually no malware for iOS in the wild.
If you're interested in iOS security, all three episodes are well worth watching, listening to, or reading. Check out the links below and then let me know, how do you feel about Apple's security and privacy focus in iOS?