The iPhone Duo Needs Apps. Claude Can Build Them.

Video authored by the channel shown, not by IANIA; all rights belong to the creator. Transcript and summary generated automatically; the original-language content is preserved.

Original language: English

Original video: The iPhone Duo Needs Apps. Claude Can Build Them. · Channel: Riley Brown · 22:58 · Watch on YouTube

Topics: Claude Code, Software engineering with AI, Privacy and data protection

Summary

Riley Brown demonstrates building an app for the newly announced iPhone Duo using Claude Code and Opus 5.5, even for someone with no coding experience. The app combines a drawing board with image search and sticker creation, then adds cloud storage and shareable, real-time boards through Convex. After testing it in the Xcode simulator, he asks Claude to refine the design and features, and says he will open-source the project on GitHub.

Key points

The tutorial uses a Mac, the Claude desktop app, and Xcode 27.1 beta to build and run an iPhone Duo app in the simulator.
The app idea combines an Excalidraw-style board on one side with image search and sticker creation on the other.
The initial prototype is built in Swift with Claude Code and tested in the simulator.
Image search uses a SER API, and remove.bg is used to remove image backgrounds.
The first version stores data locally; the creator later integrates Convex for cloud storage and real-time updates.
Convex enables share links so other people can view boards in a browser.
The creator iterates on the app’s layout, sticker animation, search, and filtering existing stickers.
He says the app will be open-sourced on GitHub, with setup instructions.

Chapters

Start	Chapter	Summary
00:00	Building an iPhone Duo app with Claude	The creator introduces the project and outlines the hardware and software needed to build an app for the iPhone Duo.
03:37	The app idea and initial setup	He describes an app with a drawing board and sticker generator, creates a project, and runs a basic Swift app in the simulator.
06:45	Creating the first prototype	Claude Code builds the initial board and sticker app, using image-search and background-removal APIs.
10:55	Adding Convex and shareable boards	After explaining Convex, the creator integrates it so boards can be stored in the cloud, shared, and updated in real time.
16:41	Testing and refining the app	He asks Claude to improve the interface, add a sticker animation, and make existing stickers searchable.
20:56	Open-sourcing the project	The creator checks the app’s orientation, requests a public GitHub repository, and recaps the tools and workflow.

Quotes

Today we’re using Opus 5.5 to build an iOS app, but not an ordinary iOS app. — 00:00

Please make a basic Hello World app. Build it and then run it in the simulator. — 05:43

We just generated this app in a single prompt. — 10:23

And guess what? We can see the updates in real time. — 15:36

This is a total of five prompts and then I open sourced it. — 22:28

Concepts and entities

iPhone Duo, Opus 5.5, Claude Code, Xcode, Convex, SER API, remove.bg, Swift, Excalidraw, Riley Brown

Full transcript (original language)

00:00 Today we’re using Opus 5.5 to build an iOS app, but not an ordinary iOS app. We’re going to build an app for the iPhone Duo. This is the brand new Apple device that was just announced. And every time Apple releases a new device, a few people build the first great apps. And now you don’t need to know how to code to build a great iPhone app. Especially because Anthropic just released the best coding model in the world that’s actually affordable. Today I’m going to build an iPhone Duo app

00:31 from scratch with Claude Opus 5.5 inside the Claude app. Even if you’ve never written a single line of code in your entire life, you can build a highquality app with Claude if you follow these four steps. The first step in building an iPhone Duo app is downloading everything you need to make it work. And if you’re following along with me to build an iPhone Duo app, here are the four things that you’re going to need. The first one is hardware. The next three are software programs that you can download on your computer. The first thing that you’re

01:01 going to need is a Mac. I’m using a MacBook Pro M4, but I’m pretty sure any newer MacBook M1 and beyond will work just fine. And then to write all of the code and do all of the building, we’re going to be using the Claude app. And this is just the desktop app that I have on my computer. You can download this app. All you need to do is go to Google and type in download cla desktop and you can very easily find it right here and

01:31 you can download it for MacOSS. The next app that you’re going to need is you’re going to need Xcode and this is going to allow us to test it on a simulator for the iPhone Duo. So this is an iPhone Duo simulator and we’re going to be using claw to generate the code. We’re going to be using the simulator to test and we can even rotate the Duo. We can open the Duo and we can open an app that I created yesterday which is a clone of Muse. And so this is why we

02:03 need simulator. And so in order to get the simulator, you need to get Xcode. So you need to go to the Apple App Store on your computer and type in Xcode and you need to download it to your computer. And then once you have Xcode downloaded on your computer, you need to go up here on Claude and you need to navigate to this tab right here, which is Claude Code. And then inside Claude Code, you’re going to run this prompt. You’re going to say, “Please make sure we have simulator working. I want to be able to

02:35 build an app, run the code, then let me test it on simulator. My main goal is to make an iPhone Duo app and run it in the simulator. Please make sure we have version 271 beta. It adds the Duo simulator. This is exactly how I set it up originally. And part of the simulator is something called devicehub that has all of the different devices. Here we have an iPhone 17 Pro. And here is the simulator for the Duo. And you need 27.1

03:06 to get the Duo. The fourth thing is I’m using Convex for a database. And I’ll talk a little bit more about that later. This one you don’t actually need to get started building the app. This one is if you want your data stored somewhere so that you could in theory create a web app in the future that shares the same database. So that’s all you need to start building a Mac computer with Claude. We’re using Claude code and then you need Xcode downloaded on your computer and you’re now ready to get started building your app. So, the

03:37 second step in building an iPhone Duo app is coming up with an idea and creating a prototype. So, here’s my idea for my iPhone Duo app. And this may seem like kind of a niche app, but bear with me here. I saw this on Twitter. This person is using the right side of their screen where they have access to stickers and on the left side of the screen, they have this little journal. And so my idea for an app will be similar to my desktop app in the sense that my desktop app allows me to search

04:09 the internet for anything. Let’s say I needed an iPhone Duo image. I can search it really quickly. I can click on this and then I can remove the background and then I can copy it and paste it to Excaladraw. So, what I want to be able to do is have a sticker or image generator on the right and then Excaladraw on the left. And I want to be able to full screen them and go back and forth between these two except I want them in to be in one app. And I want to

04:40 be able to generate stickers of anyone, right? I want to be able to look up Sam Alman and have a sticker for him. and I want to be able to generate it and create a sticker so that I can drag it over to the board and then add some context around it to create a board to better explain my ideas. Okay, so now that you understand my idea, I think it’s time for us to build our prototype. So again, we’re not going to be using Claude like the normal chat version. We’re going to be using Claude code. So

05:12 you can come up here, click on Claude Code, and what we’re going to be doing is we’re just going to press commandN. and you can see the main interface of Claude Code. And so the first thing that I always do is I’m going to create a new folder for this project and we’re going to put it on our computer. So I’m going to come down here where it says agent native landing. We’re not going to be working out of this folder. We’re going to open up a new folder and I’m going to go ahead and I’m just going to store the folder where we’re writing all of this code. We are going to put it in the

05:43 documents folder. So I’m going to click on documents and we’re going to hit open. Then what I’m going to do is I’m going to always start off with this prompt. We’re about to build an iPhone Duo app in Swift. Please make a basic Hello World app. Build it and then run it in the simulator. We’re going to build a full app right after that. I just want to get everything up and running and working. So Swift is the native language for iOS. Basically, what we’re building is an app, a plain app

06:14 that just says hello world. What I want to do is establish in a connection. Make sure that everything’s working so that we can get the app running with this simulator right here. That should only take a couple of minutes. Then we’re going to use our first prompt to build the actual app that we’re building. Okay, so it says the Hello World is running on the iPhone simulator. I’m going to go ahead and move this back over. We’ll switch to the iPhone Duo. And there you go. a very basic Hello World app running on the iPhone Duo

06:45 simulator. Okay, so now it’s time for our first prompt in building the actual app that we want to create. So here’s the app that I want to create. Build an app made for iPhone Duo. One thing I’m going to add here is search the internet and figure out how to design the best apps with the new iPhone Duo. And then it should be made to look good horizontally and it should be an app that allows me to make cool documents with stickers with real images. The right side of the app should be based on stickers. I’m giving it those two

07:16 images. One of the screenshot of the app that I saw on Twitter and then one of the image that I just generated with AI. And we are using Opus 5.5. And for the first prompt, we are going to use high. So, it will use a little bit more tokens and might be slightly more expensive, but it’s still not that expensive with Opus 5.5. And the app should be like Excaladraw on the left and a sticker generation on the right. And I’m just giving some very basic information about the app and how I want it to behave.

07:47 Now, what I’m going to say is everything should be stored perfectly inside a local database. We are going to add convex. So, we’re going to make this a database stored in the cloud later, but we’re starting off with a local database. So, every iPhone app that you create can have an a database that’s built into the iPhone. The problem is if you want to create like a team plan, no one else can see that data. It’s just you. And so, eventually we’re going to move this to the cloud. But for the prototype, we’re going to start off with the local database. So, you know how we’re actually going to be searching

08:19 images that can be found on the internet? We actually need an API for this. And so for this, we’re going to be using the Google search engine API. And we’re going to be using SER API for this. And we’re we’re going to get an API key from this, which will allow us to generate images. And then to remove the background, we’re going to be using remove.bg. I create an account here. This one, I think I’m paying $5 or $10 a month for to generate unlimited images. And I’m going to get my API key from this as well. And so now we’re going to

08:49 go back to Claude and I’m going to say for the image removal or for the image search and background removal we are using sir and remove.bg. I will paste the API keys below. This isn’t generally best practice but I do it anyway. And I’m going to just go ahead and run this. And then I’m going to paste it right here. I don’t want to do it on film because I want to keep my keys private. Okay, I’m not going to

09:21 lie, that took forever. I think it took about 37 minutes to finish. But as you can see here, we now have this scrapbook app on our device. So, here it is closed. Here it is open. Let’s go ahead and take a look at this. Okay, so here’s our app. Okay, so here’s a new document. So, I can select this right here. And so I’m just going to say Claude 5.5. Okay, that is the same font.

09:52 And so if I were to double tap on the screen right here, I could say Claude Opus 5.5. And then can I drag this? I can drag it around. Very cool. Now what I want to be able to do is I want to be able to search something. So can I type in Daario Amodai? Now we can search for it. Now, let’s turn him into a sticker. Hopefully, this works. Oh my god, this is insane. Look at this. We just generated this app in a

10:23 single prompt. And I believe we can full screen it right here. So, here it is full screen. Look at this. We created this Excaladraw app. We can create stickers. I can full screen this. Ooh, that looks really good. A clawed logo. And now I can turn this into a sticker. There it is. Now I can open up the board and drag it in. Wow, one shot we created this. It took 37 minutes to generate, but we oneshot created this app for the iPhone Duo. And

10:55 again, all of this data is just stored locally on the app right now. What we really want to have happen is we want this data to be stored in the cloud so that in theory we could share these with other people. We could make them sharable. So, we want to actually store them in a database in the cloud. And the easiest way to do this with Claude is using Convex, which brings me to the sponsor of today’s video. Every real app needs somewhere to store its data and keep it accurate for everyone using it. Convex is the back end I use for that,

11:25 and it’s built for the way that we make apps now with AI agents. There’s an official Convex plugin for Claude Code. install it once and every time you ask Claude to build something, it can set up a real database, backend functions, and file storage for you. And everything is real time. When data changes, every screen using the app updates instantly. No refresh, no extra code. Normally, your agent would have to build the syncing, the caching, and all the rules that keep your data consistent. With

11:57 Convex, that’s already done, so your agent can focus on the actual app. The plug-in also lets your agent see the app’s structure, logs, and back-end functions. So, when something breaks, it can see why and fix it. And because your data lives in Convex, not inside one app, you can start with an iPhone app today and add a web or desktop version later, all reading from the same database. Creating a Convex account is free. Ask your agent to build your next app with Convex. The link is in the

12:27 description. Okay, back to the app. And so in order to create a database, and by the way, this database will be real time. So if you have a team account within our app and I were to move things around the board, it would actually happen in real time. Convex has a real-time database that like updates really fast. So this is going to be really cool. You’re going to go to convex.dev and you’re going to make sure you’ve signed up for an account. Then what you’re going to do is you’re going to go to cloud code. You’re going to go to customize. You’re going to go to plugins. And then you’re going to discover the convex plugin. And you can

12:58 see that it should say convex by convex. This is a bundle design. We’re going to click on this and you’re going to make sure that this is downloaded. And now what we’re going to do is we’re going to come down here and I’m going to speak out this prompt real quick. Hey Cloud Code, I need you to actually make this a real time database cuz we’re going to add a team plan later. So I want this data to all be stored in a database real time. I want it to be perfect and I want to be able to make these boards sharable and send a link to someone with the with

13:30 the code or with a link so that they can view my boards with those images as well. So, I want these to be sharable and viewable by friends and on my phone. So, please make the convex database however you think you need to do it. Do it perfectly and our app is going to be amazing once you’re done. And now we can fire this off. I’m going to go eat a little bit of food and come back and hopefully we’re going to have a database fully set up. Okay, just to give you a I’m just blown away by this. Look at this. It’s 57 minutes. It’s working. And

14:02 I just said I’m testing it. It’s fine. So I I can’t wait to show you what it’s done. It’s just working for so long. So I’m just going to be like, please hurry up. It’s good. Like it’s fixing little things I didn’t ask it to fix, but it works. So just wait for this to stop and I will show you. So it’s finally done running. Look at the app that we created here. So look at this. So we can create a new document just like before. And it feels the same, right? We could say like

14:33 open AI new features, right? Let’s say I was making a Excalibur diagram and I can pin this away and then I could double tap, which still works, and we could type codeex. And then we could just type codeex logo and I could search this up, turn it into a sticker, then just drag it directly in there. That’s kind of sick. Codeex logo chat GBT logo immediately sticker them. There we go.

15:06 And then we can do Sam Alman. Turn him into a sticker. Boom. And there you go. The coolest part about all of this is now that we’ve integrated a database with Convex, we can now create a share link. So here I can create a share link and I can copy this link and I can send it to a friend. Right? So we’re in an iPhone. It should give us an option. I have no contacts in the simulator, but if we were using my actual iPhone Duo, I

15:36 would see my recent text messages here. And I could go to Chrome and look at this. I can paste this link and it gave us a convex site link. So that’s where all of them are. And look at this. It is working. The share feature works. And guess what? We can see the updates in real time. So if I edit it on here, I could say chat GPT. Look at that. As soon as I click off to the side, it shows up. So add a new one. Chat GPT. We

16:10 have a GPT image. As soon as I click off, it’s going to show up right here. Watch. Boom. Right there. GPT image 2. And I can c I can just turn this into a sticker and paste it on here. And look at that. I can move it around. This should be view only. It is. But I can share these with other people, which is really cool. Okay. So, we obviously have downloaded everything we needed. We created a prototype in one prompt and then we added another prompt which is

16:41 adding a database and share links and it worked perfectly. It did work for 50 minutes to get this right. But it did end up working. Now the final step in building our app is just to test and iterate and make it perfect. And so here’s how I’m going to do that. So I’m going to open up the simulator right here. And now we have the app. I’m going to want to make some changes to the design here because I don’t love the way this looks. Now, I’m going to open up Claude Code right here, and I’m just going to say list of things I want to

17:13 change. Now, I’m going to go one, can you please make the um main page that is shown here significantly better? Keep it creative, but I just don’t This looks very tacky and lame. So, just optimize the front end of this site. When I select a character to turn into or any image to turn into a sticker, I want that to be the little animation on the right side of the screen, which takes the image before it’s turned into a sticker and animates it into the sticker format. I think that would be like a fun little thing to have. Also,

17:45 get rid of the little text at the top that says little things very you. I don’t like that at all. And then there’s too many buttons at the top here. If you can minimize the amount of buttons, like we might need only need like one full screen button. just figure out a way to like make those a little bit tighter. And yeah, rename the app to native board. And then in the search bar, right in the search bar, as I’m going to like look up an image of someone while I’m typing it out, it should show me the names of the stickers. So like these

18:17 stickers should have names associated with them. And the name that is associated is the name that I search, right? So if I generate an image of Sam Alman, I actually want the name of that image to be saved as the search term that I originally searched for it. So that’s just how it should be saved in the database. As I’m typing them out, the stickers should filter by the things that I’ve typed in. So if I type in SAM, I can either press enter to generate it or ones that I’ve already generated I can very easily add to the board, you know, so I don’t have to like generate

18:48 ones over and over again if I commonly use the same stickers. And I can just search for stickers. You know what I mean? Okay, those are four big changes. Let’s fire it off and then I think we’re going to be good. I think we’re gonna have our app created. I mean, it’s pretty pretty good. I don’t know what else I would even add to this. Okay, would you look at that? We are done. And let’s go ahead and create a new board. We can see our stickers here. Notice here there’s less tabs up top, which is exactly what we wanted. And we can full screen this. If we type in Sam, it pops

19:21 up. So, I could say how LLM’s work and we could type in Satia Nadella. I have no idea why I’m looking up Satia Nadella. It pops up. Oh, I forgot about the animation. Wait, there should be an animation when we select Satia. Wait, so we can turn him into a sticker. Oh, there it is. Let’s go. That’s kind of cool. Bang. new co-opilot features. Now we have co-pilot or we can

19:52 type co-pilot. Oh and notice here as I type co I type chat gbt cloud and codeex popup. So this is not only allows me to like search Google images but it also sorts through my existing images. So I could type in co-pilot Boom. There we go. And then as we type co,

20:26 these stickers pop up. So this is really cool. This is looking good. And I could type uh Microsoft new AI. And then we can share this share link. Copy this link. And then I could paste it in a browser. And there you go. It works in real time. Let’s close this out. Look at that. We can add another Satia. It’s happening in real time because we’re using Convex. This is awesome. This is really fun. And there you go. That’s how

20:56 you create an app on the iPhone Duo. Okay. So, now it’s vertical when it’s vertical. That’s pretty cool. And then we can go ahead and close Let’s go ahead and close our phone here. Rotate it. There you go. So, that’s how you create an app with the new iPhone Duo. And I’m going to go ahead and make this app open source. So, I can just say, “Hey, please make a new public repo. Make sure no sensitive information is leaked in this process.” It should be public. It should

21:26 be called native board. It should be on Riley Brown’s GitHub. Please put it there. And instructions on how to set every single thing up. Assume someone has not even uh like doesn’t even have Xcode downloaded. I want them to figure out how they can very easily um get you Claude to set this up. So this by the time you see this video, this will be fully opensourced and we’ll have it up on GitHub. And there you have it. This is what we did today. We used Opus 5.5, which I genuinely believe is the best

21:57 model right now, front end, backend, probably. We use the Xcode simulator, and that’s how we’re running this right here. here. That’s how we can turn it. We can open it etc. Uh we use Serper uh the the API to or SER API to give us the image generation. We also use remove.bg which allows us to remove the background. And then Opus figured out how to add that like white border around the edge for the sticker effect. We also

22:28 use convex to allow us to create share features and it stores the data in the database in real time. And then we tested and iterated it for a few prompts. This is a total of five prompts and then I open sourced it. You can find the link in the description to the GitHub if you want to clone this app. Have at it. This was a lot of fun. Anyway, thank you guys so much for watching. Let me know what I should build when I actually get my iPhone Duo. I don’t think I’ll have it for about 3 weeks, but I want to do more

22:58 experiments. Let me know what I should build with it.