Our app looks great but I think it would be pretty cool to have the background

color change every time we press a button.

Earlier, we changed the color on the screen from interface builder's

attribute section, but I mentioned that all this was possible programatically

because all interface builder was doing was exposing the properties

on the instances of the classes that back those objects.

This means that we can also set these properties from our code.

Let's head over to The ViewController.swift file

to a view controller sub class.

Our end goal is to have the screen color change when we press

the Show Fun Fact button.

We already have it wired up to execute the code in the show fact method

since it's an IB action.

So let's add the color changing code in here.

When we change the color of the view in the label text and

interface builder, we use the RGB picker to pass in some values.

And I said that under the hood all this did was create an instance of

the UI Color class.

So let's try and create an instance of this class ourselves.

We'll say let new color equal UI and color and

UIColor is a class that's part of the UI kit framework.

Now before we do anything here let's check out the class reference

really quick in the docs.

So Help, Search.

It's a UIColor and there's a brief description

up at the top here which I encourage you to read.

And then there's a section if you scroll that talks about

creating a color object from its component values.

Right, so it is right here.

Creating a custom UI color object in a specific color space.

This is exactly what we want since all we were doing earlier was creating this color

object by providing component values in the RGB space.

There are many different ways to create a UI color instance

because color can be represented in lots of different ways.

Since we're working with RGB we're going to use this initializer method that takes

in R,G and B, red green and blue values along with an alpha component.

So only use this one.

To use this method you need to know a bit about how the RGB scale works.

On the RGB scale values go from 0 to 255 for each component.

The initializer method we're going to use however takes a value between 1 and

0 for each component.

So if we want to pass in a red value of say 223 to use in the method.

We need to divide it by the maximum value 255 to get a value between 1 and 0.

So in our method let's pass in a couple values as arguments.

For the red parameter the argument we want to specify the values is 223,

remember we have to divide by 255.0 to get a floating point value.

Next for green we want 86, so divide that by 255.0 as well.

For blue, 94 divided by 255.0 and for

the alpha value which is the opacity we want it to be fully available on screen,

no opacity below one at all.

So, will simply say 1 for that value.

And now, we have a color object.

We can now set the background color property of the view to this object.

So every view control has that parent view that we've reference before, and

we can access it through the view stored property.

Now you can also do it by using self.view to explicitly refer to

the fact this is a stored property, but I'm going to follow convention.

Now the view itself is an instance of UIView,

which has its own stored property for a background color.

So to this we're going to assign the new color object we just created.

Let's give this a try.

Let's build and run the app.

And now everything works like before, but

when we click the button look at that, we have a new color.

There's two problems though.

The color only changes once, and we'd like it to do more, but

the button is still green and that doesn't match.

Let's fix this in our next video.