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Right, so let's look at how we in or actually register all the buttons are set up, all the methods,



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fire is just up to us to implement the firebase code.



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So to do this, of course, we need, first of all, firebase off.



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And then when the in is tapped, we need a way to see what the log in or to pass over those email and



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password to Firebase.



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Now, the first thing we need to do, of course, is double check that the following is true.



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That's not empty and that's not empty, because if they are empty, we shouldn't bother making a call



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to Firebase because all these calls add up to fees we might have to pay.



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So what we're going to do is make sure we don't make a call unless the email and the password look legit.



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OK, so what I'm going to do is create a function down here called check input or validate input or



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whatever you want to call it.



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And then I'm going to return a bool on this.



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So maybe we'll call it the input valid.



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That's a more that's a better name.



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And then we'll say if input valid and if it's not valid.



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So we're going to put an exclamation then for now we're going to return.



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Of course, we can also show an error to the user.



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We can show the error down here so we don't have to repeat the code, of course.



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OK, of course, I've been playing with Colin and things like that a lot, so I always forget to put



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these in.



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So I'm going to copy that and I'm going to put it in register.



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I'm going to forget about, forgot about, because I'm not quite sure how we're going to do that flow



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when we get to that point.



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So input valid?



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Well, first of all, we have to get the email input text and we also need to get the password input



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dot text.



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Now, these are optional as in the text might not exist, but at least I thought they were optional.



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Let's see what happens.



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No, I think they're perfectly fine.



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So let's have a let email equal and let password equal.



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OK, so we have the text from those so we can do a very basic validation here.



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See, they are optional.



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OK, so if email account, what we're doing is accounting a number of characters is less than, let's



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say for an email address, you need at least four characters because it's something at something dot



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com, actually, five characters or six, rather.



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So if it's that or if pass don't count is less, then I don't know, let's say five characters, then



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we're also going to kick the user out.



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So we're going to say return false.



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And at this point we can actually show the user an error.



40

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OK, so this email is giving us errors.



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So what I'm going to do is just put an exclamation after these options because I know that the text



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exists.



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Even if there is nothing in the box, the text itself will exist.



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So this is one of those rare cases where you can actually force unwrap the optional again, if you don't



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remember what options are they?



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Just a box that might contain the type of value you specify or might contain nothing.



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Go back to my old courses on Swift, my previous courses, I should say.



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They will explain all of that stuff for you.



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Otherwise we are going to return.



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True.



51

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OK, so that's the validation of the input sorted later on, perhaps we can well, why?



52

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Why later on?



53

00:04:01,910 --> 00:04:05,450

Let us create a new file and let's do it now.



54

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Swift file.



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00:04:09,000 --> 00:04:17,040

Utilities, my favorite kind of thing, so let's import the UI kit.



56

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And call this what it should be.



57

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Don't need to inherit anything, and then we have some code, so function show alert.



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Now, let me see how I've done this in my previous project, because there's no point in dragging you



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guys through this.



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OK, I'm trying to copy this and I'll talk you through why it's doing what it's doing there.



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So to show the alert, we need to have access to The View controller because the View controller contains



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the navigation controller that will allow us to display the alert, as in we need a reference to The



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View.



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OK, so that's what we're pulling in there.



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If you didn't do that, there are other ways of architecting this where you could have your utility



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class access to The View, but we're not going to do anything complex here.



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Then we have an alert.



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We have an action which is OK, and we're just going to pass over the title and message.



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So this is generic.



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Finally, we're going to present that particular view controller.



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Feel free to pause and copy this code if you need to.



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OK, so let's go back to our orfeu controller.



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So if that's wrong, we're going to say utilities.



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Utilities.



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Utilities don't show alert, and what's the title?



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I'm about the title in this case, of course, is an error.



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The message is email or password to short.



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That's a good enough error, and they're going to pass over the View controller itself, so I don't



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know why it's not coming up with the code completion for us here.



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But I was just doing what it's doing, I guess.



81

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OK, so we can test that out.



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00:06:31,120 --> 00:06:32,820

We can go over to our iPod Touch.



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And if we put in those values that are too short, then we should see that Arabic's pop up.



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So I'm just going to put a little something there.



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And perhaps they're going to get rid of the keyboard and then I'm going to hit it with Log-in, wasn't



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it?



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They go email a password too short.



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Of course, register does nothing.



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00:06:58,860 --> 00:06:59,480

Oh, no.



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00:06:59,490 --> 00:07:00,840

We set it up in register.



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So it does do something.



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Login to short, OK.



93

00:07:05,280 --> 00:07:07,260

And now if it goes longer



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and we do it, we get nothing happening because we've just fallen through that filter.



95

00:07:15,030 --> 00:07:20,040

Now, obviously, in a production app, you might want to give the user just a little bit of information.



96

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So you'd split out this check and this check to let them know exactly what they were doing wrong.



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00:07:26,160 --> 00:07:31,950

So say to them, look, you need a longer password, you need a correctly formatted email, and so do



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the email.



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00:07:32,520 --> 00:07:37,830

You do something called regular expressions, which are a nightmare, but it's something you have to



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do.



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And you can find regex on the Internet pretty easily for what you need, especially stuff like email



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addresses.



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So anyway, we're going to leave that one there.