All language subtitles for 2. What are Flutter & Dart Packages

In order for our app to be able to play sound both on the iOS ecosystem as well as on Android, we're
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gonna use some Flutter packages to help us to do that. Before we can start incorporating a package to
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help us play sound in our Xylophone app,
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we first have to understand what Flutter packages are and how they work.
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So in order to do this we're gonna use a really simple package so we can see all steps of the process
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and then we're gonna apply our knowledge to be able to use a package to get our Sylophone app to play
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sound a little bit later on.
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So first, what exactly is the package?
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Flutter packages are open source libraries of code that other people have created which you can incorporate
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into your project with minimal effort.
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Now in order to browse all of the Flutter packages, head over to pub.dartlang.org/flutter.
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And these are packages that are specially made to be compatible with Flutter projects.
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Here you can see on the home page, they've got a whole bunch of the top packages.
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So these are the most popular and the most frequently used packages. And we're going to be using some
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of these a little bit later on.
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But you can also search for Flutter compatible packages in the search bar here. And this is what we're
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going to do.
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We're going to search for a package that generates words.
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And once you hit enter, you'll notice that there's a lot of packages that might vaguely match that search
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term. But what's really helpful is that on this website, you'll see that each of the packages are shown
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with a description but also a score.
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For example, out of the ones on this page the ones that actually do what we want it to do, which is something
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that generates words in English,
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there's two that I can see so far.
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There's the English word package and there's the random words package.
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But you can see this one clearly has a much higher score.
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So if we click on this, you can see that the score is made up of a number of things.
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And it's ranked in the search by how popular it is, how many people have used it,
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what is the health of the package,
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so how good does the code look,
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how frequently is this package of code updated by the author.
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And finally we end up with an overall score.
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And clearly the higher the better.
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So you can see this one English words has a 100 points, but the other one, the random word, only has
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85.
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And it got some points docked because there were less people using it.
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So when you're looking for packages, be mindful that there might be lots of packages that do the same
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thing. But when you look at the score, you'll be able to pick from all of the packages one that might
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be the most robust and best suited. A lot of these packages are also made by the Flutter team.
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For example, on the home page we've got a Flutter package called shared preferences.
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And when you look at the right bar here, you can see that the author is the Flutter team. And it's been
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uploaded by a bunch of people who work at Google.
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So when you're looking for a package, this might be another indicator that this is a good package to
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trust and to use.
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Let's go back to that package we found, the English words package.
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And let's take a look at how we can use it.
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You can see that this package contains about 5,000 most commonly used English words. And it also
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has some functions that will be useful when you're trying to work with English words.
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So for example you can print the top 50 most used nouns in the English language or calculate the number
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of syllables in a word.
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And we're going to take this package and use it inside our project just to see how it all works.
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Whenever you find a package that you want to work with, the easiest way to get started is to click on
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the installing tab and see what the authors say about installing this package.
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So step one is to depend on it.
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So we have to head into our pubspec.yaml file, and we have to paste in this line where it specifies
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that we want to use the English words package as a dependency.
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So we're saying that our project is going to depend on this package.
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So let's open up our pubspec.yaml and under where you see it says cupertino icons,
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we're going to paste in what we just copied over.
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Notice that cupertino icons is also a package that you can find inside the Flutter packages.
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And this is a Flutter package that's developed by the Flutter team.
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And what this does is it allows you to use the iOS icons inside your Flutter app.
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And this is usually included in all of these starting files when you're creating Flutter apps.
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Now that we've added our dependency in here, what does these carat symbols mean exactly? There's a couple
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of ways of adding these dependencies into your YAML file.
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The easiest way is to simply add the name of the dependency.
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So in this case it would be english_words and that should match with whatever you see at
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the top here, before the numbers start.
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So in this case this package would be cupertino_icons and our previous one would be called
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english_words.
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Now what this does is it will tell Flutter to grab this particular package called English words from
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the default location which is that same website that I just showed you just now, pub.dartlang
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.org. By not having any numbers
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after this, we're saying grab any version you like, anyone that you can find essentially.
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But if we go ahead and add a virgin number after the name of the package, we're telling Flutter to download
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any version of this package that begins with the major version of three.
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So this means that if the authors of this package updated their code to version 3.6 or 3
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.7 or even 3.2.1 etc. It's all fine.
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We're happy to use it. But if the authors have updated their package to version 4.0.0,
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so as long as the first number changes to the next one, then we're not going to take it.
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The reason is because when people update their code base, there can be breaking changes so they might
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have done something that might just crash your app.
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And because we're using these as dependencies which means that whenever we update our dependencies, we're
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going to grab the latest version of the package and incorporate it into our project.
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If something changes from their side, then it might break our code.
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Now how do I know about this?
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Well of course the Flutter documentation details this.
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In this section of the documentation where they talk about using packages, they talk about all of these
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different versions and what they will mean.
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So my recommendation is whenever you're using a package from the Flutter packages, always specify the
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version and add a caret or that little top hat symbol in front of the version to limit it to that major
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version.
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That way you get most of the benefits and less of the downsides.
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Now that we've added this to our pubspec.yaml file, the next step is to actually install the package.
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And in order to do this, we need to run pub get. And you can either do that in the terminal as they described
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in the documentation, or if you're working inside Android Studio, all you need to click on is packages
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get. And this will run the same command and it will go to that website
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we were on previously. pub.dartlang and it will download this package and incorporate it into your
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current project.
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So now when you click on your external libraries folder, you'll notice that we have one extra Dart package.
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And if you scroll down, you'll find our English word package now added into our project with very little
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effort from our side.
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So now the final thing we need to do to be able to use it,
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we have to import it into our code. So let's copy this and paste it to the top of our main.dart and
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then we can get started using it.
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So most of the documentation for the packages should appear on the read me page and commonly you'll
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see a few examples in the examples tab. And this kind of tells you how you could work with this package
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and what it can do.
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So in our case, what if we wanted to get a English adjective and we want to display it on the screen?
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Well instead of having a container, I could have a text widget and the string that's going to be displayed
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in the text widget is going to come from my brand new package.
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Now I can see that here, they're tapping into something called nouns and I'm gonna do the same.
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So for my text, I'm going to use nouns which you can see,
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this comes from.
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And if we wait here for a bit, you can see our quick docs tells us that this will list the top English
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nouns, and the list is sorted in order of frequency of use in the English language.
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And so if we select this and we write .first to get the first noun in that list of nouns, and we go
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ahead and run our app, right here in the top left corner, you can see the word time,
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if you have really good eyesight.
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But let's move it into the center to help you see it a bit better. So that says time and I could go into
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my list of nouns and instead pull out the one that's last in the list. And that happens to be the word
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apology.
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Now I can also instead of using nouns, I could get some adjectives. And let's see what the last adjective
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is, naval.
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Okay.
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Now you might ask, well how did you know that there is this thing called adjectives? Because if you try
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something else, like verbs, it doesn't really work. That doesn't exist.
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How did I know that there's nouns and adjectives?
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Well remember that we've already downloaded the entire package that's called English words into our
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project. So you can always just look inside.
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Have a look inside the source folder and you can see that there is a words folder which contains adjectives
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.dart and nouns.dart and also all.dart.
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So these are all of the top 5,000 English words.
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These are the top English adjectives and these are the top English nouns. And you can see that this is
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just a list of things.
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And when I said nouns.first, it gave me time. But when I said nouns.last, it gave me the last
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one in the list, which was apology.
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So it's really easy. All that this package does is it contains a whole bunch of words. And depending on
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what you need, you can pull it out and use it inside your app.
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Now this is a really simple package that I picked to be had to demonstrate and show you how it all ties
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together and how it works.
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But if you search through here, there's all sorts of packages. There's packages that make it easy for
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you to build an app that uses in app payments, or something that lets you work with Apple Health and
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all sorts of packages.
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Now the way that you should view packages is to think back to maybe the days when you played with Lego.
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And I remember building a lot of Lego houses because they were just kind of easy to do.
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I didn't have that much imagination. But sometimes you might need, I don't know, a tree right?
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Like one of these tropical trees. I think that's how they looked,
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right? Now you could probably build the tree from scratch yourself, but what if you had all these little
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components like a tree or a window or a car already pre-built for you and all you need to do was to
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click it into place? Then that would make the whole job of building out your tropical house way way easier,
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right?
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And that's how we work with packages.
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Packages are essentially a bunch of code that somebody else wrote to achieve a specific goal. And because
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they spend all the time building it, they're kind enough to upload it to the website to share it with
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the world. So that you or I,
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when you need that particular functionality, don't have to spend the three months or six months that
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it took to actually build it.
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Instead we can simply plug it in as easily as we plugged in that plastic tree. In the next lesson,
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we're going to be looking at how we can use a sound playing package to be able to play our Xylophone
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sounds.
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So all of that and more, I see you on the next lesson.