You can now run iOS 4 as an app on your iPhone - how to install
It’s been 11 years since the debut of iOS 4 at a March event, while the iPhone 4 was announced at WWDC in the same year. Since then we’ve seen huge changes to iOS, with a flat redesign from iOS 7 and also seeing it on bigger iPhone devices.
But there’s a growing nostalgia for software, as many remember what their first device was or the applications they used that inspired them to start a career out of them.
iOS is in the same vein, and with this innovative app you can try out iOS 4 on your iPhone 12 Pro right now.
- Meet Apple's new updates: iPadOS 15 | iOS 15 | watchOS 8 | macOS 12
- Here’s the best deals for an iPhone in June
- It’s time for Skeuomorphism to return to iOS
A developer by the name of Zane has lovingly re-created a previous version of Apple’s iPhoneOS into a single app, available to be tested right now on your iPhone.
It’s Skeuomorphin’ Time
Far from just being the home screen of iOS 4, everything about the old operating system has been remade into a single app called OldOS, where you can switch between Maps, Settings, Safari, Game Center and much more.
It’s very surreal to use it on an iPhone 12 with a bigger screen than the 3.5 inch display that the iPhone 4 had, but it works well regardless.
It’s been fully coded in Apple’s new SwiftUI language, which is a way of building and distributing apps, something that the company has been showcasing across WWDC 2021.
Sign up for breaking news, reviews, opinion, top tech deals, and more.
It’s a great effort from Zane, and it does make one wonder as to whether an iPad version is on its way too, especially as he has touted it as open source, which means other developers can add even more features to OldOS if they wish.
Today is Launch Day 🚀Introducing OldOS — iOS 4 beautifully rebuilt in SwiftUI.* 🎨 Designed to be as close to pixel-perfect as possible.*📱 Fully functional, perhaps even usable as a second OS.* 🗺️ Fully open source for all to learn, modify, and build on. pic.twitter.com/K0JOE2fEKMJune 9, 2021
How to install OldOS
You can install the app using app testing site TestFlight, although at present the enrollment list looks to be full, so it depends on whether Zane opens up even more places to the beta program.
But if you’re feeling daring, he has also posted the full source code for OldOS onto GitHub, so you can open it up in Xcode, compile it and have it run on your iPhone. Although this is really only for developer territory, unless you like a challenge for the weekend.
- Get a head start on Prime Day 2021 deals

Daryl is a freelance writer and author of two books—The Making of Tomb Raider and 50 Years of Boss Fights. A third book, the follow up to ‘Tomb Raider’, comes out in 2026. Having worked at TechRadar previously as a software writer from 2021 to 2023, Daryl understands how software can benefit users, as well as having an interest in how accessibility features can benefit others.
With over a decade of experience, his work has been featured in Tom’s Guide, SUPERJUMP, Pocket Tactics, Radio Times, The Escapist, and more.