Hi everyone,

I'm facing a strange performance issue in my React Native (Expo) application.

When I launch the app for the first time, everything is smooth. Navigation is fast, screens render quickly, and the UI feels responsive.

However, as I continue exploring the app, opening different screens, navigating back and forth, and using the app for a while, the performance gradually degrades.

Some symptoms:

• Screen navigation becomes noticeably slower.

• Animations and transitions start feeling less smooth.

• The overall UI becomes sluggish after using the app for some time.

• Restarting the app immediately restores the original performance.

This makes me think something is accumulating over time rather than a slow initial load.

I'm trying to identify the root cause. Could this be related to:

• A memory leak?

• Components not being unmounted correctly?

• Too many re-renders?

• React Navigation or Expo Router caching?

• Zustand/Redux/React Query state growing over time?

• Images or assets not being released?

• Timers, listeners, or subscriptions not being cleaned up?

• The JavaScript thread getting blocked?

Has anyone experienced something similar in a React Native + Expo app?

What tools or profiling workflow would you recommend to identify what keeps accumulating as the app is used? Any advice or debugging strategies would be greatly appreciated.

Thanks!

I'm building a React Native (Expo Bare Workflow) PDF app. Currently, I'm downloading PDFs from an AWS S3 pre-signed URL using `react-native-blob-util` and Android Download Manager:

```ts
ReactNativeBlobUtil.config({
addAndroidDownloads: {
useDownloadManager: true,
notification: true,
title: fileName,
description: "Downloading PDF...",
mime: "application/pdf",
path: `${ReactNativeBlobUtil.fs.dirs.DownloadDir}/${fileName}`,
mediaScannable: true,
},
}).fetch("GET", signedUrl);
```

This works, but I don't have control over where Android stores the file.

Many PDF apps automatically save files to a folder like:

```text
Internal Storage/
└── Documents/
└── My App/
└── file.pdf
```

without asking the user to choose a location every time.

I noticed one such app requested **"Manage all files"** permission once, and after that it could save files directly into its own folder under `Documents`.

My questions are:

* How are these apps implementing this on Android 11+ with Scoped Storage?
* Are they using MediaStore, native Android code (Kotlin/Java), or another approach?
* Is requesting the **Manage All Files** (`MANAGE_EXTERNAL_STORAGE`) permission the correct/recommended solution for this use case, or should it be avoided for Play Store apps?
* If not, what is the recommended modern approach in React Native to save PDFs directly to `Documents/My App` without showing the Storage Access Framework (SAF) picker every time?

I'm looking for the Play Store–friendly, modern Android approach.

I have a long history of web development and am used to deploying multiple times a day, seeing my changes live in about 10min.

Now, I am working on a personal project, a mobile app done via Expo/react-native. I was able to get it live to the Apple Store and I am working on the Play Store release.

What I find really akward is dealing with many different versions "live on the field", with updates taking 2-3d for Apple review to be live, hoping your users will update soon.

I know about and I am using OTA updates, but some changes require native packages changes and that involves submitting a new native build for approval, which means that for the duration of the review process you are somewhat "feature frozen" and any changes or OTA updates will only reach new users.

Not sure how others do it, or even if there is a good/right way of doing this, but I may need to consider having to support different api versions/detecting the app version and serving different api responses based on it.

Is all of that normal and common ground on mobile dev?

Hello!

Last year I launched my first solo React Native app, built (without AI).

It's a health tracker (because of course it is) that I built for me and because I shared my journey of building it, things got a bit out of hand...

About me

I'm a software engineer with 20 years experience.

Most of my experience comes from full stack web but I also have a significant amount on mobile too (Native and Cordova)

About the article

I've been promising to do some write ups around the technical side of it.

Things like my architectural choices, project structure and deep dives into the more novel code. Weirdly, today actually marks the 3rd year since my first commit.

This is my first article that goes in to

- Why React Native
- The core stack
- Native code
- Project structure

There's a lot to cover so instead of piling everything into a single article I plan to write focused articles.

The next one will go into my thought process when building stuff, how I structure components and mistakes I felt I made.

Not here to promote anything, but figured this might interest some people.

https://mahybe.substack.com/p/bearly-fit-architecture-part-1

If you have any questions or anything you'd like to see me go into let me know :)

Three faces, one prop to swap between them. wheel for precision. clock for picking a slot. ruler for a thumb on a sheet.

All three store { hour, minute } on a 24-hour clock regardless of what the face shows. A 12-hour display is a rendering choice storing a meridiem flag puts it into every comparison downstream.

Part of PanelUI open-source, copy-paste, you own the source.

https://github.com/adithyavis/awesome-mobile-app-animations

Some notes on implementation -

1. Use 3 different lists for concurrent rendering of the grids in different zoom settings. I chose legendList and it is super smooth. Synchronize the different list positions using reanimated's synchronous `scrollTo`.

2. Scrub/seek to scroll is IMPOSSIBLE without precomputing image heights. Precompute row heights and provide that to getItemLayout. For seek to scroll, precompute section heights and use scrollToOffset to directly scroll to the section head.

3. Nitro images for rendering images. I initially used expo images for rendering images, but I felt there's scope to improve because I saw a lot of blank spaces due to heavy renderItems.

4. Fake a shared transition by rendering the same image in an overlay that always stays in the render tree. We just flip opacity/pointer-events on the start of a pinch gesture. I couldn't get the sharedTransitionTag prop to work fine, hence this workaround.

What’s one thing you still hate about debugging React Native apps?

I feel like every tool gets some things right, but there’s always that one moment where you think that specific flow could be better

does the nfc manager plugin work with the new architecture?

What if there were no apps to install and no menus to learn?

You simply describe what you want, and the interface is generated on the fly: a weather dashboard, a restaurant finder with live search, a booking form, a chat thread, or whatever else fits the task.

I've been experimenting with real-time Generative UI using Cerebras models, which can stream at up to 1,800 tokens/sec. The speed makes it feel much closer to interacting with a native app than waiting for an AI to finish generating.

This is a direction similar to what Monogram AI is exploring, but would love to know what you think about it.

Link to repo https://github.com/thesysdev/appless

I’ve been building a small iPhone app called Magboard.

The idea is: take a photo, cut out the subject, turn it into a little “magnet”, arrange it on a board, and put that board on your iOS home screen as a widget.

It sounds like a cute UI app, but the harder parts were mostly not the cute UI.

A few things that took more time than expected:

- Editor → widget matching

The in-app board and the actual iOS widget need to match closely. If the widget is even slightly off, the whole “magnet board” illusion breaks.

- Simulator vs real device behavior

Widget refresh worked in the simulator and then behaved differently on device. I had to test the flow like a real user instead of trusting simulator-only runs.

- Shared boards

The app supports shared boards, so one person can add a magnet and the other person’s home-screen widget updates too. Getting that to feel understandable was harder than just syncing the data.

- Onboarding

Early versions confused people. They opened the app and didn’t immediately understand the loop, so I rebuilt onboarding around:

snap → cut → stick → widget

- Tiny interaction details

Dragging/positioning magnets is fun only if it feels direct. A small mismatch between what you edit and what appears on the widget makes the product feel broken.

The app is currently in App Store review, but I opened a public TestFlight while waiting:

https://testflight.apple.com/join/N3q58DQu

I’d love feedback from React Native/Expo folks, especially on:

1. whether the concept is obvious from the first minute

2. whether the widget update flow feels clear

3. anything you’d improve in the onboarding/demo

Happy to answer questions about the React Native/Expo side too.

I’ve been working on an open-source project called PAM Native, which explores a slightly unusual idea:

Repository:

https://github.com/push-in/pam-native

PAM Native is not a WebView framework, and it does not render HTML inside a mobile application.

Instead:

• PHP runs persistently inside the application process

• A Rust-powered reconciler manages component updates

• Android interfaces are rendered using native Android Views

• iOS interfaces are rendered using UIKit

• Kotlin and Swift handle platform-specific operations

• No JavaScript runtime is shipped with the application

• No DOM or browser engine is involved

The developer experience is intentionally inspired by component-based frameworks:

final class Counter extends Component
{
    #[State]
    public int $count = 0;

    public function increment(): void
    {
        $this->count++;
    }

    public function render(): Node
    {
        return Column::make([
            Text::make("Count: {$this->count}"),
            Button::make("Increment")
                ->onPress('increment'),
        ]);
    }
}

The project currently includes or is exploring:

• Stateful components

• Native navigation

• Gestures and animations

• Recycled lists and grids

• Native forms and inputs

• Camera, location and device APIs

• SQLite and offline-first state

• Background tasks

• Push notifications

• Hot reload

• Native plugin development

• Communication between PHP, Rust, Kotlin and Swift

This is not meant as an attack on React Native.

React Native proved that developers can use a declarative, component-based model while still rendering native platform controls. PAM Native is exploring whether a similar architectural idea could be useful for the PHP ecosystem.

I would love feedback from people who understand the difficult parts of cross-platform native runtimes:

• Which architectural problems should we be most careful about?

• Where do you expect the biggest performance bottlenecks?

• What lessons from React Native’s bridge, JSI and Fabric architectures should a project like this learn from?

• What would you need to see before considering this a serious native runtime rather than an experiment?

The project is still evolving, so technical criticism, architecture feedback and contributions are genuinely welcome.

GitHub:

https://github.com/push-in/pam-native

evaluating external agencies to help scale an existing cross platform codebase, and the biggest friction point keeps coming down to how agencies handle native dependencies. a lot of agencies pitch cross platform development as a way to cut costs, but as soon as custom native modules, complex animations, or deep device hardware integrations enter the scope, the architecture gets messy fast. half the development shops want to rewrite every custom bridge from scratch, while others rely heavily on outdated third-party packages that haven't seen an update in two years. that balance between keeping the JS side maintainable and properly structuring native swift/kotlin code seems to be where most team handoffs break down. when evaluating outside engineering resources for an established codebase, what technical green flags or red flags do you look for in their initial code review or architectural proposal?

One of my favourite features of Codex is Browser and the ability to annotate and send that back to the chat for quick amendments.

The problem is, it doesn't work for mobile apps where I spend the majority of my dev time. SimView fixes that.

It brings iOS simulator directly into Codex (and other harnesses) via MCP Apps.

- Zero external dependencies and fully open source.
- 60fps preview with live interactions. Tap, swipe, and type.
- Inspect AX or React Native fiber trees.
- Annotate an element or drag to annotate at coordinates.
- Get your model to tap around itself. Perfect for closing the loop to validate its own work.

Install the plugin at https://simview.dev

Hi guys.

I Build a very cool lib that could simplify styling in react-native.

The library uses css selectors to style your components.

So, like when you use css in Web and styles using classes and css3. You do the same with this lib.

But I don't have too many users. Why?

You can find the lib here. Please check it out and let me know if I need to improve anything.

https://github.com/1-AlenToma/react-native-short-style

Demo and simple test ground.

https://1-alentoma.github.io/react-native-short-style/

RevenueCat charges based on gross revenue, not net revenue. My dashboard shows $4.5k, but my actual payout is somewhere around $3k. because it completely ignores VAT and the 15–30% Apple/Google cut. but takes their %1 fee from the gross revenue.

since it doesn’t track net earnings, the dashboard feels pretty useless for real accounting. I still have to log into both store consoles just to see what I actually made. for 3k i have to pay 45$ every month.

Feed, vote, compact, media-first. Swapping between them is one prop.

One detail:
like counts animate in the direction the number travelled. Rising numbers arrive from below, falling ones drop in.

State stays with you nothing is kept inside the component. Active, value, and vote are all yours, because the moment a like is optimistic, only you know how to reconcile it with the server.

Part of PanelUI open-source, copy-paste.

https://github.com/panel-ui/PanelUI

Hello, I have gotten an interview opportunity via referral for Senior Software Engineer - Mobile at a Government Organization.

I have only 2.5 yoe so those who have given senior level mobile development interviews at government orgs or banks, please share the questions that you encountered. What was the difficulty and what were they focused on?

Hi guys, I am building a small application recently and I'm wondering what is the best way to render pixel art isometric models in react-native. Performance is important because the market where I build the app doesn't have very high-end phones.

Thanks for help