Saving and Loading a High score (Swift in Xcode) Video Lecture | Swift in Xcode: The Complete iOS Development Guide - App Development

hi everybody today i'm going to show you
how to save and load data with Swift and
xcode so let's go ahead and get started
in this tutorial we want to accomplish
basically we have a score and a high
score now when you reset the score we
want to keep this high score but not
only keep the high score when the app is
first loaded we want to kill the process
of the our app load it back up and it
will always have that high score so
let's get started
alright let's open up Xcode and create a
new Xcode project this is going to be a
single View application our product name
I am just going to call mine Saving
Private Ryan you guys can call this
whatever you want your language will be
set to Swift in our devices will be set
to iPhone click Next and create and now
I'm going to make this a bit bigger and
they're going to go into our main dot
storyboard and I'm going to add in our
label this first label will just be our
score label like so so we will have our
score displayed inside of this label and
let's make it a bit bigger and center it
then we also will have our high score
label so let's just take that score
label duplicate that and change the name
of it and change the text inside of it
to high score and let's Center it make
it a bit bigger so there we have our
score and our high score alright and now
let's create a button and this button
will actually be our counter item so
this will actually change the score
anytime you click on it so we're going
to put Center this inside of our scene
and I'm just going to pretty up by
changing the background to some nice
colors that's a bad color there okay and
we can erase the text that's on the
inside there alright there we have it
and now let's lastly enter a reset
button so this will reset our score
completely so we can see what our high
score
is now like so we'll just put that right
in there all right now let's go ahead
and connect these up to our
viewcontroller.swift file so open up our
assistant editor up here in the top
right corner and we're going to connect
our score by just saying right by right
clicking or control clicking and
dragging from our score label and this
will be our score label connect that up
and then I'll right-click or ctrl click
and drag from our high score and this
will be our high score label so now that
you have those connected up connect your
buttons which are our reset buttons so
connect that up reset connect and this
one will be our score our counter we'll
just call this our counter button this
is going to add more to the score now we
want actions to be happening when we
click these buttons so right click or
control click and drag from reset and
we're going to make this in action
make the connection type in action and
now we can insert an action so this will
be our reset action connect and then
right-click or control click and drag
from this button and this will be our
counter action oh I meant to make that
an action counter action so there we
have it and now we can put things inside
of these actions that we have and lastly
I'm just going to Center all of these so
I'm going to right-click or control
click and drag from score and center it
horizontally and Center it vertically so
that it will stick to any size device
that we have so just do this real quick
alright now that those are all centered
up and they're going to work on any size
device that we plan to choose and we can
close our assistant editor and go over
to our mate viewcontroller.swift file
now we want to create our variable so
our first variable will be our score so
save our score equals zero and then we
will have another bear
Abell and this will be our high score so
we can say high score equals zero all
right now that we have those scores all
set up let's go over to our reset action
and we want to have actually we don't
want to reset anything right now let's
go over to our counter action and we're
going to say any time this counter
action is pressed where when that
counter button is pressed we're going to
say you score plus plus so we're adding
one to the score every time and then
we're going to say if the score so if
open parentheses close parentheses score
is greater than greater than our high
score label I'm sorry our high score not
label then we want things to happen so
open curly bracket enter close curly
bracket and inside of this we want to
say high score is equal to is equal to
score so we're changing our high score
to the score that is being created that
is being added to and now we need to
update these labels so they can actually
show this so in order to do that we can
say our counter action we can say score
label dot set text dot text is equal to
NS string open parentheses and we're
going to have format NS string
so our NS string this is going to be an
open quotation mark close quotation mark
percent at and right before that percent
at inside of the quote eight open
quotation mark close quotation mark we
are going to have score like so so now
this is going to add substitute this
percent at for whatever argument we have
right after this so now we can replace
this argument for our score integer that
we have created so now let's go up here
to our if statement and we can say high
score dot
I'm sorry high score label dot text is
equal to NS string and this is going to
be the exact same thing format except
this time we're going to say high score
: percent at and then our argument
afterward will be our high score in
integer that we have created all right
so now if we were actually to build and
run this you will see that when we click
this button we get an issue and actually
we have a problem these should be
percent is not percent ads because for
whatever reason app means pretty much
any object I means it's an integer so
you want to say percent I instead of
percent app now let's build and run this
and as you will see we will click on
this button right here and we grow the
score and the high score now let's add
our reset value and I'm just going to go
over to my main dot storyboard and fix
the problem with this now if you ever do
mess up on your constraints like I just
did I have made it equal to the width of
the scene and that is not what I want so
I'm just going to erase those right over
here in our in our size of size
adjustments over there so now we can do
that for this one too and building up
and now we have this box and our reset
and our score in our high score so now
if we click this box you will see that
it goes score eight high score 8 and we
don't have anything for reset so nothing
will happen so let's go over to our view
controller dot Swift and make things
happen inside of our recent action so we
can say score is equal to 0 and then we
update that label by just going down
here I guess and doing that like so now
it's as simple as that there's not too
many things that are going to be inside
of this reset button
now we click reset it resets the score
but again it keeps the high score as you
will see and when we click on this the
score it will go up to the high score so
now if you were to click command shift H
H which is the equivalent to just double
it double tapping your home button so
you can end the process of your
application you can just end save it
private private ryan' and you can open
that up again and as you will see the
high score and the score went back to
zero so now let's go over to our main
our project again and now we want to
save the high score so we want the score
to go back to 0 because that's normal
but we want the high score to save so in
order for us to do this we go over to
our review did load and first of all
we're going to load actually not right
now first we need to create a default so
we can save our default or we can we'll
call this high score default is equal to
NS user default dot standard user
defaults and now if you go into your
high score default you can set the Val
set a value for key so you can say dot
set value and we're going to set this
value our high score and then we're
going to save it as the key of our high
score so basically what all this is
doing we're creating an NS user defaults
which basically means we're accessing
the core data of our application and
storing it inside of there and then
we're going to grab that out of it later
on with this key that we created right
here this is going to be anything that
you want you could call it high score
blah blah it doesn't really matter I'm
going to call it high score and we're
going to access it by this name and you
also may want to make sure that your
capitals and everything are properly
done that way you don't get any errors
later on now we are saved we are setting
this value high score to the key high
score so now that that is done we can
easily say
high-score default dot synchronize
synchronize after that alright and now
we actually want this to load up in our
scene so when we are seen viewed it when
our view loads we actually want this to
set as the high score so we can easily
do this just by saying first we need to
grab this part right here where it says
var high score default equals NS user
defaults dot standard user defaults and
we're just going to put that right
inside of our viewdidload for some
reason I don't know the exact reason why
but you can't call an NS user defaults
or your standard user defaults inside of
this super where you could access it
from any from any function you need to
call it in every function that it's
referenced in so now that that's over
with we need to say high score equals
high score default dot value for key and
we're going to again add that key that
was inside of here so just copy and
paste that right in there equals and so
high score equals a high score default
value for key and we're going to store
this as an NS integer like so and add an
exclamation point to initialize it in
your scene now one thing you will notice
I'm going to build and around this right
now one thing it's not going to work
you're going to get this excessive bad
instruction didn't understand what this
meant for a while but basically it means
that something is not loading up
properly so in order for this to happen
you need to say if high score default
dot value for key and this is going to
be a high score is equal to nil so
basically if this high score is equal to
nothing then we will add this into our
high score so basically it was trying to
add something from nothing so it's not
going it didn't work properly and again
this needs to be equals equals new now
if we built and ran this we will see
that you're not going to get that
exception code actually you will of
course you will that's how programming
goes so actually the problem is with
this problem with this statement right
here you need to say it's not equal to
nothing so if the value high score is
not equal to nothing so if there's
something inside of that we're going to
load that inside of this high score
value that we have now we can build and
run this and as you will see we have our
high score of course there's nothing
added into the high score at the moment
we can reset our score and go home
delete the process and go back into our
saving private ryan' and oh one last
thing you will see that it is working
because the high score isn't growing as
the score increases so we need to
actually load the high score inside of
our high score label so we can say high
score label dot text is equal to NS
string open parentheses format and this
is going to be ice open printed open
quotation mark close quotation mark high
score colon and then our argument value
or this going to be percent I and then
our argument value will be high score
and let's build and run and now you will
see that it loads up with our high score
as we did before
again you can kill the process and see
that it's working every time and reset
the score and la-dee-da
there you have it that is out you save
your counter or your score inside of
Xcode with Swift so I hope you enjoyed
it thanks for watching that's it for
this tutorial if you enjoyed it be sure
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much for watching and I will see you in
the next one
no I did not get punched in the face
cold Spurs