Solution: Add user authentication

(upbeat music) … - [Instructor] Okay, so let's go over this challenge … of adding user authentication. … So the first thing we want to do is fetch the password … for this username. … So after line 65, I'm going to add a couple of blank lines … and I'm going to optionally bind … the password fetched from the keychain. … So I'll say if let pwSaved for the saved password. … And I'll call the secure manager retrievePassword … and pass in UN for the unwrapped username. … So if we got a password, we want to compare it … against the password they typed in. … We also unwrap that to pw. … So I'll say if pwSaved is not equal to pw … then we're basically done. … They entered their password wrong … and we're going to call completion nil. … So that means they shouldn't get stored, … they shouldn't be set as logged in, … and we're not going to pass back a user login instance. … Otherwise, if we didn't get a password, … we want to store the user and we can do that here. … So I'm just going to cut lines 75 to 77 …