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Let's change our size class back to the default which is the iPhone XR and we want to fix our problem
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where our background image gets cut off when the orientation changes.
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So how can we do this?
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Well, essentially, we need this background to resize itself, so that all four edges of that image is tied
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to the four edges of our screen, so that the top edge here is always sticking 0 pixels to the top of whatever
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orientation the screens in. The right is always sticking 0 pixels to the right of the screen.
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The bottom is zero from the bottom and the left is zero from the left. But, of course, we can't just adjust
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our image like so
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because as soon as we flip back to the other orientation it stays exactly the same.
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So we need to add some rules or Constraints onto this image view. And that is what we're gonna tackle
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in this lesson. To begin, let's make sure that you also have the same size class selected, the iPhone XR,
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and that it's in portrait mode,
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and then we're going to select our AppBrewery Background image view, and we're going to resize it so
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that it fits the entire screen of our iPhone XR. And then we're going to make sure that our logo is
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bang in the middle of our screen.
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So this is kind of our desired look at least in portrait.
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From here, we're going to add some constraints to our AppBreweryBackground, so that even when it's in
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landscape or on a different device, it still is touching all four sides of the phone and it's stretching
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to fit the entire screen.
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And then we're gonna go and click on this button right here,
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the little square button which is going to allow us to add a Constraint. And the Constraint that we
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want to add is to specify a zero pixel distance from the top of the phone, zero from the left, zero from the
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right, and zero from the bottom.
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So we're going to click on these red lines and turn them from these dash lines to solid lines to activate
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those four Constraints, and then we're simply going to click on this button.
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Now, if you don't see zero in each of these boxes, then go back and make sure that your background is
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placed exactly like so,
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and it's a fitting the entire screen.
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Once you're done, go ahead and click Add 4 Constraints.
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And now we go into our landscape orientation.
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You can see that our background image view is now more or less stretching to fit the entire space. But
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there's a couple of problems here.
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Firstly, why is it that our background is not going all the way to the left and right? What's going on
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there?
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Well, we can actually explore our Constraints and figure out what's gone wrong with them by expanding
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our Constraints here and we can see what these constraints or rules are doing to our User Interface.
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So the first one is a rule that says the right side or the trailing side, as highlighted here, of our
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AppBreweryBackground should be equal to the safe areas trailing.
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So this means that when our phone goes into landscape, the safe area is the area which normally contains
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either the battery information or the signal information of the phone. And at the bottom of the iPhone
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XR, it's the home button essentially, it's the part which you swipe to go back to the home area.
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So often if we're creating an app that has buttons on it, then we don't want it to be in these safe areas.
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So we'll define rules that keeps it out of these areas.
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But in our case, because it's just a background, we want our background to actually cover the entire screen,
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rather than have this sort of blocky effect.
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So we actually don't want it to be set to the safe areas trailing
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and in fact, we want it to be set to the superview.
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So this is our current element. The superview is the view that contains this element. And the superview
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that's at the base of our View Controller is always going to be covering the entire screen.
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So we want to define this constraint. Rather than relative to the safe area,
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we're going to define it to the superview. So this one right here. And we're going to say that it should
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be equal to the superview's trailing.
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So now our AppBreweryBackground, the trailing, the right side edge, is now fitted to be zero pixels from the
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trailing edge of our view.
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So that's the one that's highlighted in blue right here.
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And if we now go into landscape, you can see it's now fitting right to the edge of that right side or
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the trailing side.
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So let's go ahead and fix the same thing with our leading view.
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So you can see we've got our AppBreweryBackground leading set to be equal to the safe area leading.
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So let's go ahead and change that from safe area to the superview.
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And now when we go into landscape, you can see that it looks perfect as it is. Now
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you can see that each of these rules when you click on them you can view them in more detail in the
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attribute pane. And you can see the rules that have been set up here that set the Constraint between
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a first item and a second item and the relationship between them.
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So for example, if I wanted my AppBreweryBackground app to stop at the safe area, then I would change this
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to my safe area and change that constant to zero.
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So the top of my image view is now zero from the top of my safe area.
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And if you want to see where the safe area actually is, you can simply click on it here, and you can see
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where it stops on the top and the bottom, and also in the landscape orientation as well.
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Let's restore that Constraint back to what it used to be
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which is where the top is equal to the top of the superview.
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And let's look at another thing.
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If we take a look at the trailing, so the one on the right, it's currently set to the superview's trailing,
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but we can also set it to be relative to the margin.
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So the margin is that thing that pops up when we have an element that we drag to the right or to the
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left.
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You can see that blue line that pops up. And often when you have a button or when you have a logo, you
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don't want it to be right to the edge because it's hard to read.
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And instead, you want it to have a little bit of a margin to the edges.
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So in that case, you can define this to be relative to the margin of the superview's trailing area.
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So if I select that, then change my constant to zero and hit enter,
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you can see it's now limiting my background to that margin.
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So these are some of the things that you can do with your Constraints. And when you add them using the
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menu here, they don't always get added the way that you think it will,
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you can have a little bit more control over it if you click on the dropdown list.
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So, for example, if I select my logo here and I click on here, then you can see that I can define it relative
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to the safe area or to the view, and I can change the distance or the value from those areas. So our background
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is now pretty much sorted. And if we take a look at all the different device sizes all the way from small
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ones to large ones, it's basically adapting it to fit the entire screen background.
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And even when we change the orientation, it still looks pretty good.
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The next thing to do is to figure out how we can layout our logo. And to do that, we need to learn about
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alignment. And that is what we're gonna do on the next lesson,
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so I'll see you there.