Most people have been in the situation where they send a message and then have to promptly follow that up with a clarification and a "curse you, autocorrect." Apple is hoping to put an end to that, according to a patent filing.
According to the patent, all autocorrected words on an iOS device will be underlined with a blue line. This will make it easier to spot when words have been changed, allowing you to double check if your meaning is still clear.
Of course, the system still relies on the user actually scanning over their message, but an indicator should make it quicker to spot an autocorrect word than reading over your message.
The patent was filed to the US Patent and Trademark Office in July 2015. As with all patents, there's no guarantee when, or even if, we'll see the system implemented.