How does Apple turn off the display of the candidate verification code?

You can choose to turn off the automatic password filling of face ID and password in the settings. It is reported that the new function of the verification code of ios 12 system is the automatic filling of verification code. This function mainly reads the verification code in the short message automatically, and then fills it in automatically, which saves users the trouble of manually entering forms in Safari and other applications, and brings users a seamless registration process experience.