TheseusOpen source Swift package

iOS 27 Liquid Glass, backported to iOS 13

I want the same UI and the same feel on every iOS version my apps support. So I backported the Liquid Glass experience to iOS 13: blur, refraction, glare and spring animations, drawn with Metal.

Open source on GitHub

One UI on every iOS version

It matters to me that an app looks and behaves the same on every iOS version it supports. Xcode 27 removed the old-design opt-out, so an app rebuilt with the iOS 27 SDK gets Liquid Glass on new systems and the old look on the rest. Theseus closes that gap.

Liquid Glass on older iOS versions

Package.swift

dependencies: [
    .package(
        url: "https://github.com/valzevul/Theseus.git",
        from: "1.0.0"
    )
]

Three controls and the glass they are made of

Tab bar

The glass capsule floats over your selected tab.

Slider

The knob lifts into a clear glass capsule while you press or drag it, or snaps to positions if you need a stepper.

Switch

A toggle whose knob lifts into glass as you press, flick or drag it.

Glass view

The core building block: a glass lens for your own components, or a translucent overlay on its own.

What you get

The iOS 27 Liquid Glass look, running on devices from 2019
Metal GPU rendering, with a fallback for older hardware
A tint for each view, mirroring the native Glass.tint API
A clear to tinted setting for the whole app, as iOS 27 gives users
Accessibility support out of the box
Spring-based morphing animations

SwiftUI

Theseus is a UIKit library. For SwiftUI, the repository includes UIViewRepresentable wrappers for the glass view, the tab bar, the switch and the slider.

Questions

Can I use Liquid Glass on iOS versions before 26?

The system's own Liquid Glass needs iOS 26 or later. Theseus draws the same look itself with Metal, so it runs on iOS 13 and later.

Can I still opt out of Liquid Glass in Xcode 27?

No. Apple's documentation for the UIDesignRequiresCompatibility key says the system ignores it when you build for iOS 27 or later.

Does Theseus work with SwiftUI?

Theseus is a UIKit library. The repository includes UIViewRepresentable wrappers for the glass view, tab bar, switch and slider. The SwiftUI demo needs iOS 15.

What happens on old hardware?

Theseus renders with Metal where it can and falls back where it cannot, and it adapts the effect to the device.

Why iOS 13 and not lower?

Metal is marked iOS 13 and later in the simulator SDK, so a lower deployment target fails to compile for the simulator.

Is Theseus free?

Yes. It is open source under the Apache 2.0 licence. Add it with Swift Package Manager.

Theseus