Name: Swift教程--初學者全科課程 (Swift Tutorial - Full Course for Beginners)
Uploaded: 2021-01-14T10:24:22.000Z
Duration: 3 h 9 min 58 s
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Welcome to learn swift programming for beginner's lesson one.

未來簡單式

You're gonna learn about what they are had to declare them and swift code, and furthermore, how to use them.

All right, so let's get started for the rest of the lessons in the Siri's, we're going to be working inside this app called X Code X Code is the tool that Apple has provided for people to build APS with and inside X code.

You're gonna be able to create your user interfaces.

You're gonna be able to write the code to express the logic in your app.

Even so, that's why this is where we're going to start in learning Swift.

We're gonna be writing this swift code inside the app that you're actually owned to use to build ups with in the future.

So this is where you're gonna get X code.

Just go to your browser, go to developer dot apple dot com slash ex code.

Or you can launch the Mac app store on your computer and search for X code there.

If you're on the Web page, you can see that there's this big blue download button up top.

Now, Ideally, you want to make sure you're using the latest version of X Code, and right now, as of this recording, it's eight, and you can check your version if you go to X code.

Ah, you can see it here in the welcome screen.

And you can also go up here two x code about X code, and you can see what the version is.

If you are a PC user in your running windows, there may be some additional work you need to do before you can run X code.

Or you might have to use an alternative solution to build IOS ups.

So check in the description below for PC solutions.

However, if you are a PC user, don't let that discourage you.

Personally, I lost about 2 to 3 years of learning Iowa's developments simply because I didn't have a Mac and I didn't want to get a Mac.

But these days there are alternative solutions.

You don't actually have to buy a Mac computer, although I eventually did.

Anyways, now that you have X code, and after you've installed it, it's a pretty large install.

It's pretty big program, so I might take some time.

But after you have it installed and you launch it, you're going to see this welcome screen.

You can see here that when you want to create an app for iPhone, iPad, Mac er, whatever you're going to go to create a new X Code project, and that's going to start a full out project for you to build a nap in.

But here, we're going to start a new playground because that's going to allow us to type some code quickly.

It's gonna let us run that code and see the results, and we're not committing to building in a project.

It's simply like a sandbox or a playground, as it's named.

Now, if you don't see this welcome screen, what you can do is just go up to file Neil and hit Playground right there, and that's going to start a new playground for you as well.

Or you could just hit this button, get started with the playground, so that's gonna launch this dialogue for you, and I'm simply going to leave the default name their platform should be Iowa's, and I'm going to save this on my desk cop.

Okay, so after your playground runs, you'll see up here, it's doing a whole bunch of stuff.

Ah, launching Simulator, getting it ready.

And when it's done all that, it's going to say, Ready?

But when it doesn't say ready and it's doing something, then chances are whatever you're typing here is not going to show up on the right hand side.

Okay, we're gonna start with a quick tour of this playground window here.

So down on the left hand side, I have a bunch of line numbers.

Now, if you don't have these and you want them, they can be useful at times, especially when I'm teaching and I need to refer to line numbers.

You can go toe X code preferences, and you can go to text editing, and you can simply enable line numbers there.

Now, this area right here is where we're going to type our swift code, and it's already got a bunch of stuff for us right here, which we're going to go through in a second on the right hand side, you're going to see a quick preview of the results of what you type there.

Now, a lot of people have trouble with getting output to show up on this right hand side based on what they type here.

Um, well, one of the things that you can check is just in this status bar up here.

You're going to see that it for a brief second there there was a little spinner because it's evaluating your code here.

Um, if you wanted to show up, just make sure it's as ready to process your next command.

And, you know, you should see that output there.

Alternatively, there is a trade down here which you may not notice because it's hidden.

At first, you can hit this button to show that the bug area, or there's also this little button here to hide the different panels.

Okay, but we don't need to see all of that, but this debug panel may be useful.

Ah, when we start to output things here, this is called a console area where we can use swift commands to output things.

This blue icon here is to execute the code in your playground.

So if you can't get things to show up on the right here, try clicking this button to run your playground.

Right now it's blue because you can see there's a little drop down arrow there.

If you click and hold it, you can see whether you want to switch it to automatically run.

And that's going to run the playground whenever you type something, or you can set it to manually run and you can see now it's great out.

So if I type in some new code, it's not actually going to change or display what I have on the right hand side here.

Unless I click the play button to run it, so I would recommend to have it set toe automatically run.

So now that you know the main areas of the playground, let's get into the meat of today's topic variables.

And in fact, what we have here is a variable in swift, a variable hold some data.

It could be a reference to an object, or it can even point to a function which are things that will get into the future.

But for now, we're going to say that variables hold data.

Now, as you can see from this example, line of code a variable has a couple of distinct parts.

Variables need to be declared before they can be used.

So this var key word is used to declare a new variable following the var keyword.

You have the variable name in this case, it's S t r.

So it's got the var keyword and it's gotten to variable name now taking a look at the whole line.

What we have on the right hand side there, that's some data.

We did say that variables hold data right in that equal sign in between the variable name and the piece of data.

So what we're doing in this line of code is we're declaring a variable called str and then a signing that piece of data to that variable.

So now jumping back into the playground, let's see the effect of that I can say something like print, which is a key word that is going to print something to that console area down below.

So if I say print and then in the parentheses I put str you can see that it's printed that hello?

Play out s rough lying down there on the right hand side.

We can see a quick preview of that and notice that there's a slash end here.

And that is basically, um, just denoting that there's a new line associated with that print statement because, ah, the next time I print something, it's gonna be printed on the next line.

So you don't see that here because a new line is just, um, a carriage return or white space.

You can't really see it, but in here in this preview, it's visualized as that slash and which is just a new line.

So let's take a look at a couple of different pieces of data that we can store into variables.

So I'm going to declare another variable here called a, and I'm going to assign a number into it.

So just bar one and I mean it clear another one called B, which I'm also a sign one, and I want to show you that you can perform operations between the variables or on the variables.

So, for example, I can save print A plus B, and you can see here that the result in the consul here is to now notice that what I'm using the variables in an equation or an operation like this I don't need to use the key word far, because that's only for declaring variables, right?

So this little part is declaring the variable, but when you use them afterwards, you just need to refer to them by name.

A times be okay, so variables hold data and you can perform operations on variables.

Now you can change the data that the variable is holding so I can say something like a equals two now, right?

In fact, actually, let's not do it down here.

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Swift教程--初學者全科課程 (Swift Tutorial - Full Course for Beginners)

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character

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