[hannasanarion]

I think you misread me. IPhones are almost certainly vulnerable to some kind of cold-boot attack, yes. That doesn't mean that it's easy to break into them. Cold-boot attacks are highly circumstantial.

If the San Bernadino terrorists shut down their phones before their murderous rampage, or if they ran out of battery before the FBI got into their house, sorry, no cold boot for you.

Cold boot only works if you have physical access to the unlocked, powered-on, in-use device. The "data ghost" in memory that cold boot attacks take advantage of is only there for seconds.