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There also are more things you can set up of course, 

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one thing I want to dive into are the over the air updates though which you control with the updates

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key in the app.json file.

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Now that's a neat feature, which means that people running your app on their device no matter if it's

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just running in the expo client because they scan such a barcode which as I mentioned isn't too useful

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or if they really downloaded it from the app stores,

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as long as you build your app in the managed expo workflow, you get the over the air update functionality

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built in and that means that if you change something in your code, let's say here on this screen we change

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something, we change some titles, some functionality or we even add a brand new native module,

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no matter what you do, whenever you publish this update with the expo publish command, all your users,

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even if they installed the app from the app stores will get this update in their app the next time they

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open the app

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and that's important. You can configure the functionality here in the updates key. Again in the official

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docs, you learned more about this update key and what you can set there. What you can set,

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for example is if it's generally enabled which by default it is

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and with this fallback to cache timeout thing, you can configure how long the app when users launch it

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on their device should check for updates and try to load them before it displays the recent available

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version. By setting this to zero, you're saying whenever the app launches, it immediately displays what

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it has. It looks for updates behind the scenes and for the next launch, it might then take them into account

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but it doesn't try to look for updates and download them before actually loading the app.

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Now you could change this to let's say five seconds,

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this is a millisecond value, so five thousand milliseconds which is five seconds.

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This would mean that when people launch the app, they will see the launch screen for up to five seconds

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which is of course quite long because after loading everything else, expo or your app tries to look for

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an update and if it finds an update, it tries to download it and take it into account.

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That might be done in five seconds, it might be done faster in which case your app will also launch

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faster but if it takes longer than five seconds, then it'll continue with the updating but not immediately

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load it but instead load the most recent version that is available. Now it's of course up to you what

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you prefer,

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this approach makes sure that users have the fastest possible startup experience but they only get your

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updated code the next time the app is launched.

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This approach or setting this to an even higher value like 10 seconds means that users get newer versions

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more frequently or quicker because they get it on the next app launch already

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but the downside is that the app launch might take a bit longer, which is maybe not what you want.

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So it really depends on which type of app you're building and which type of users you're targeting, what

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you want to set there.

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If it's a business app let's say which you distribute to your employees which needs to be updated all

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the time and where the user experience is not that important,

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you might want to take a value like 10 seconds here,

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if it's an app you share with normal end users around the world, you might want to go for a faster start

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up time to provide a good user experience and sacrifice update speed for that,

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so users would then only get the update on the next launch after this launch.

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With all of that out of the way, let's actually have a look at all of this and also at this over the air

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update feature.

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I changed a couple of settings here and therefore what I'll now do is I'll run expo publish again,

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still that's the command which will not get it in the app stores but which will share it

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here on this expo page so to say. So I run this command and we could have still optimized our assets

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with expo optimize

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but since we don't really have images included in the app other than the icons here which are generated

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and optimized by expo anyways, this shouldn't be a problem,

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so I can just run it like this and wait for this to complete and then I will test this on an Android

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device because there, the advantage of course is that we can use this barcode here.

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So now once this is finished, the cool thing is we'll immediately have this new app available by scanning

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this barcode and thereafter, I'll show you how we can get over the air updates without even scanning

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the app barcode again because that's the idea, we get any updates without scanning again,

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it's pushed to our app the next time we launched the app. So let's wait for this publish process to

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finish and the URL is still the same as before because I haven't changed anything about my slug here

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which is part of the that URL or anything else.

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So now here's the expo app on my Android device where I can now scan this barcode and therefore now

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the app launches here on Android. Now you see I got the splash screen, I got the app running here and I can

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of course also use it, for example I can take an image here. So that all works the way it should work

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on my device here

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and now let me show you this over the air updating functionality.

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See that add place title here at the top?

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Now let's change that in our code.

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So let's go to the code here

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and on the screen here in the new place screen where we set this title,

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let's change this to add new place,

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it's a tiny change but still.

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So now if I run expo publish again, this app will be bundled up and will be published to

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the expo servers again.

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So let's wait for this process to finish and it's done

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and now let me show you this live updating.

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I still have the app running here,

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so of course this does not change whilst the app is running, so of course here we still have the old title.

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But now let's say I was away quite a time,

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I closed this here and now I relaunched the app.

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If I now go to the new places screen, I still see the old title.

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Now that makes sense if you think about the updating strategy we used.

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I made sure that the app launches as quick as possible and downloads a new update behind the scenes,

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so that's what happened

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now, this was the first relaunch of the app on my device after updating it.

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So let's say I'm again away quite some time and I relaunch it again, by the way here you can see the

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adaptive icon in action.

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Now if I go to that screen, you'll see add new place as a text because now this is the second

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launch after the update. In the first launch,

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we downloaded the update and installed it so to say, in the second launch we're using it.

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Now the app on the device technically didn't change, just what's in there changed, our Javascript code

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changed and since we have this expo wrapper, this means that expo can take this into account and use

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this new code

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and this will also work if you publish your app to the app stores because there whilst you will build

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a standalone app and people won't need the expo client, you will still include that expo client app into

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your standalone app

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as I mentioned earlier,

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so your standalone app kind of has the thin expo wrapper the expo client built in and wrapped around

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your app,

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that's why over the air updates will even work there.

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And speaking of that, we now test this a lot,

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we tested this all with just expo and with scanning the barcode.

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Now let's dive into how we can really build this app and publish this app for the app stores.