text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
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So all of the React Native components,
the React components sorry, | 875.58 | 3.88 |
we've changed to React Native
components and now we have-- | 879.46 | 3.388 |
Oops, something's breaking still. | 882.848 | 2.322 |
Prompt is another one
of those browser APIs | 890.42 | 3.9 |
that just does not exist in
the React Native world which | 894.32 | 2.7 |
caused our code to crash. | 897.02 | 1.39 |
And so rather than using
one of these browser | 898.41 | 2.96 |
APIs let's just replace it with
some hard coded text for now, | 901.37 | 3.21 |
maybe something like to do, number,
and then whatever it's ID is. | 904.58 | 8.15 |
And rather than
incrementing ID down there | 916.511 | 1.749 |
let's actually increment it up here. | 918.26 | 1.5 |
And so now it works. | 922.51 | 1.15 |
So we have to do number
one, to do number two | 923.66 | 2.42 |
and you can see how we add those. | 926.08 | 3.31 |
And so we'll fix the
style in the future, | 929.39 | 2.1 |
but basically does
anybody have questions | 931.49 | 2.64 |
on going from React Web to React Native? | 934.13 | 3.39 |
What we did there was just replace
all the React Web components | 937.52 | 3.36 |
with the React Native components. | 940.88 | 1.89 |
And it is almost as easy as command
effing and replacing like that. | 942.77 | 4.52 |
Great. | 951.291 | 0.499 |
And so how are you going to go
about styling those components? | 951.79 | 3.27 |
So in React Web the way
we did that was just | 955.06 | 2.9 |
by adding a class name and then
styling in CSS, but in React Native | 957.96 | 3.89 |
we don't have this concept of CSS. | 961.85 | 3.492 |
So the way that React
Native handles that | 965.342 | 1.708 |
is by actually using JavaScript objects
for styling and what that gives us | 967.05 | 3.33 |
is the ability to use dynamic styles. | 970.38 | 4.11 |
Object keys in these objects
are based on CSS properties, | 974.49 | 3.35 |
so we have stuff like margin top,
margin bottom, margin padding. | 977.84 | 5.726 |
And the layout system
that we used is Flexbox | 983.566 | 1.874 |
and so, if you're familiar
with the Flexbox system in web, | 985.44 | 2.416 |
it's almost exactly the
same in React Native. | 987.856 | 3.104 |
One of the key differences
is that rather than | 990.96 | 3.06 |
defaulting to row we default to
laying out things in columns. | 994.02 | 7.48 |
So, in React Web, we have this
concept of pixels or percentages, | 1,001.5 | 3.52 |
but in React Native we actually
use unit-less numbers for length. | 1,005.02 | 4.36 |
Which is good because there
are so many different devices | 1,009.38 | 3.48 |
that this runs on with
different pixel densities | 1,012.86 | 2.19 |
that having a unit-less number allows
us to abstract that pixel density out. | 1,015.05 | 4.18 |
The style prop, so the way that
you style a given component | 1,022.52 | 3.72 |
is by assigning that JavaScript
object to a style prop | 1,026.24 | 3.89 |
and it can actually
take an array of styles. | 1,030.13 | 1.87 |
And so, if you wanted to have a bunch
of different class names in React Web | 1,032 | 3.78 |
you'd just start adding those
with a space in between. | 1,035.78 | 3.6 |
But in React Native you handled
that by passing an array of styles. | 1,039.38 | 3.075 |
So let's go ahead and add styles
to this app that we have here. | 1,045.109 | 7.121 |
So first, let's go ahead
and style this view. | 1,052.23 | 2.24 |
And so right now, as you see, each
to do has a Delete button and a | 1,054.47 | 6.27 |
to do right under it, whereas in web
we had the Delete button next to that | 1,060.74 | 4.24 |
to do. | 1,064.98 | 0.5 |
And so let's try to
figure out exactly how we | 1,065.48 | 2.32 |
can get that Delete button over
here and the to do to be next to it. | 1,067.8 | 4.7 |
And so does anybody have any ideas
about how we might want to do that? | 1,072.5 | 4.59 |
We know we're going to
have to pass a style prop, | 1,077.09 | 2.43 |
and we know that it's
going to be an object. | 1,079.52 | 3.45 |
And so this looks weird to
have those double curlies | 1,082.97 | 2.46 |
but the outer curlies
mean, hey here comes | 1,085.43 | 2.7 |
some JavaScript and the inner
curlies are just an object | 1,088.13 | 3.06 |
literal like we've seen before. | 1,091.19 | 2.88 |
And so how might we get
those to dos to be in a row? | 1,094.07 | 3.61 |
So we saw before that React Native uses
Flexbox in order to handle it's layout. | 1,100.35 | 6.81 |
And so we can just say, hey we want
the flex direction, rather than being | 1,107.16 | 6.63 |
column by default, let's set it to row. | 1,113.79 | 2.818 |
And so now we have the Delete
button next to the to do. | 1,119.42 | 5.19 |
But it's annoying me a little bit how
that button is slightly below the text. | 1,124.61 | 5.77 |
And so how might we get those
items to be aligned to center? | 1,130.38 | 5.36 |
Well in Flexbox we have this
thing called align items | 1,135.74 | 6.12 |
and then you just say, hey
align those to be center. | 1,141.86 | 3.66 |
Then all of a sudden we
have it aligned center. | 1,145.52 | 2.27 |
And just confirming that
delete button does indeed work. | 1,151.55 | 3.841 |
Great. | 1,155.391 | 0.499 |
Anybody notice any other
bad style bugs over here? | 1,155.89 | 3.45 |
So look at this. | 1,161.89 | 3.25 |
So most phones will have some
nav bar, and that nav bar | 1,165.14 | 5.72 |
will have stuff like if you're
connected to Wi-Fi, the time and etc. | 1,170.86 | 3.87 |
But that first view is actually
going all the way to the top. | 1,174.73 | 3.95 |
And so how might we get all this
content to be slightly moved down? | 1,178.68 | 3.46 |
So how would we do that in Web? | 1,186.29 | 2.75 |
AUDIENCE: Add a margin. | 1,189.04 | 1.98 |
SPEAKER 1: Yeah we would add a
margin or some padding or something | 1,191.02 | 2.75 |
to move the content from
the top slightly down. | 1,193.77 | 4.09 |
And so we could do that
in React Native as well. | 1,197.86 | 3.68 |
So you can say with this view, let's
actually put a padding on the top | 1,201.54 | 7.57 |
and let's just say something like
50 which is somewhat arbitrary. | 1,209.11 | 4.741 |
And now we've gone ahead and
moved that down slightly. | 1,213.851 | 2.249 |
But what if we wanted to move it down
exactly the same amount as the status | 1,219.46 | 6.08 |
bar? | 1,225.54 | 0.5 |
Well there's this great
tool called Expo which | 1,228.96 | 2.85 |
we'll talk about in length later today. | 1,231.81 | 1.84 |
They're also the people
who designed Snack. | 1,233.65 | 2.3 |
And they actually give you
this thing called constant | 1,235.95 | 2.61 |
so we can do import constants from Expo. | 1,238.56 | 3.515 |
And we can actually say,
hey padding top rather | 1,245.56 | 2.2 |
than assigning an arbitrary value of
50 let's do constants.statusbarheight | 1,247.76 | 8.76 |
and that will actually give you
that exact status bar height | 1,256.52 | 4.05 |
even if you're on different phones. | 1,260.57 | 2.174 |
And so, again, we'll
talk about Expo and we'll | 1,262.744 | 1.916 |
talk about importing and
exporting later today. | 1,264.66 | 3.17 |
But just FYI there's this thing called
constants.statusbarheight which will | 1,267.83 | 3.99 |
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