They have been integrating hardware from the beginning, not making it all themselves. What they do, though, is demand the ability to vet and fix vendor firmware.

>Apple has been building its own hardware from the beginning

do you mean designing? I'm not familiar with any point in time where Apple was building phones, but maybe i'm mistaken.

A quick google search indicates that even the first generation phones were built by Hon Hai.

They acquired Intel's modem division, so that may change in the future as well.