How do you know UITextField will confirm an autocorrection when return key is pressed?

Let's be more specific, the return key is actually set to "Send", and with auto correction enabled. When auto correction does appear, pressing return key will only confirm the auto correction and not actually intend to send the text. The question is how do you know that there's an auto correction happens? I cannot tell in textFieldShouldReturn.

By the way, I also开发者_如何转开发 considered "Did End On Exit" event, but I find the keyboard always hides as long as the event linked to a method, which I want not.