Okay, so far even though what we did was pretty cool,

what we have here is mostly just an if statement with different keywords.

So each of these is an if else if else if else if else.

So why can't we just use an if statement?

Well, let's see how Switch Statements really shine by

adding a few more values to the array.

So in here, I'm going to add a comma, and I'll add LGW, add another comma,

then I'll add JFK, and finally ORY.

Now these new additions are the second international airports in London,

New York and Paris respectively.

So let's go back to our Switch Statement.

You'll notice now immediately that when the for loop executes and

once we hit LGW, JFK and ORY.

In addition to DXB, we don't know which cities these airports are in.

So now we've printed out four times, I don't know which city that airport is in,

because we hit the default statement four times.

We want to print the name of the city depending on the airport just like before,

but now we have some new airports.

If we were using an if statement, to get this to work we

would have to add an else clause for the new airports, an else if clause.

Or we could use a logical operator to create

one compound expression for that city.

For example, we do something like this,

if airportCodes[0] ==, double equal, so check the equality.

Will say LGA or airportCodes[0] == JFK,

then we'll print New York.

As you can see this is already a bit hard to read and

there are a couple places where we can make mistakes.

The string that we write here, we could forget to do double equals,

we could do not equals by mistake.

It's a bunch of things, right?

With a Switch Statement, it's so much easier.

Each case can match against multiple values and

that's why I said pattern earlier.

And to do this we simply separate each value with a comma.

So in this case, we'll say, if the airport that we're considering,

if the value that we're considering is either LGA or JFK, then print New York.

So now you'll see, New York is printed at the beginning when we hit LGA.

And then the second last value is New York again.

And that's all it took to make this a compound expression.

So let's do this for the rest.

So, we'll say, if this is either LHR or using a comma we'll add two values,

we'll say, LGW : print (London).

And finally, if this is CDG or ORY, then print Paris and that's it.

There's no limit really to how many values each case statement can match against.

If you look in the results area, you'll see that New York, London, and

Paris were matched two times each.

Hong Kong was matched once.

And we got the default result for

the Dubai International Airport because we didn't provide a case for it.

But let's take this a step further.

Let's go back to the other example we used when discussing ControlFlow,

the temperature.

Now this time let's use Fahrenheit to be fair.

For the purposes of weather, temperature in Fahrenheit goes from 32,

freezing point, to 120, in some extreme cases.

Rather than writing out a specific value for

the temperature, I'm going to generated it randomly.

I'm gonna write some code.

Don't worry about what's going on here.

So, I'll do, import GameKit.

I'll say, let randomTemperature

= GKRandomSource.sharedRandom.nextInt

(upperBound: 150).

So don't worry about what's going on here, I'm just using some of the code

Apple provides to generate a random number that goes from 0 to 150.

We'll talk more about functions in the future and

you can come back to this example and poke around.

For now it just makes the example a bit more interesting to work with.

You'll see that 11 was our randomly generated number.

And every time I hit Enter or evaluate the code again by hitting the play button,

we should get a new random number.

So earlier we used a compound if else statement to

print out the items of clothing we should add to our wardrobe based on the weather.

Let's combine two of the new concepts we've learned in this course.

Ranges and switch statements to make that logic easier.

So again we're going to start with the switch statement, and

the value that we're going to switch on or the value that we're going to consider.

In this case, the value we want to consider and

match against a bunch of different values, is this random temperature.

We'll say, randomTemperature.

Key statements support matching across a range that we provide.

So, rather than specifying an upper and lower bound for temperature values

using an and operator, we can use ranges to provide a range of values.

So here's what I mean.

For a temperature range of 0 degrees to 32 degrees, that's mind numbingly cold.

So forget clothes, just don't go out.

So, here we'll start with the case statement again but

instead of providing a single value to match against we can provide a range.

So we can say 0..

Or period period and then we will use an angle bracket of 32.

So if you remember what we learned in ranges, this is the half open range

operator which means that our values go from 0 to 1 less than 32.

So 32 is not included, it's the values from 0 to 31.

Now if the temperature falls anywhere between this range,

if random temperature is anywhere between 0 and 32.

Then we're going to print (Forget clothes,

you are basically a popsicle).

Let's add a few more cases.

So in here we'll say case 32, so this range starts at 32 and

goes all the way to 45, including the number 45.

Then we'll print (:It's quite cold.

Oops, syntax error.

It's quite cold.

You'll need a jacket).

In the next case, which will go from 45, all the way to 70.

And you'll notice we have a mistake here, over here we're including the number 45,

and here our range starts at 45.

So what if the value is 45, which one do we match?

We'll fix that by using a half open range operator.

Then we're going to print ( It's a bit chilly.

I recommend wearing a light sweater).

For the last case, let's go from 70 all the way to 100.

And in this case, we'll say print ( It's quite hot!

T-Shirt weather!).

And then if the temperature is higher or lower than this, we'll say default,

(Don't even bother to go out!).

Okay, so now look at that, the randomTemperature generated was 146.

Is 146 between 0 and 32?

No, it's not.

Is it between 32 and 45?

It's not.

We can match on every single case and will return false.

So finally we hit the default statement which prints out,

(Don't even bother to go out!).

Let's hit Enter again.

So that we generate a new temperature and

now the new temperature which is random is 25.

Okay, 25 is between 0 and 32.

So we hit that first case and it says, (Forget clothes,

you're basically a popsicle).

Isn't that awesome, a switch statement can match on more than just a single value.

Hopefully, this glimpse into the flexibility of the switch statement

should show you why their preferred over if statements.

ControlFlow helps us add logic to our code and define various paths for

this logic so that we can take different actions based on a set of conditions.

We've learned a lot of new things here, so

right before we wrap up, I've provided two challenges.

One, is somewhat straightforward so I'll let you tackle that on your own.

The second requires a bit of explanation, and

there are different ways that you can solve it.

So, I've provided a video to explain the problem and

another video with the solution.

In between the two, I trust that you will try your best and

work through the problem yourself.

Have fun.