valzevul/theseus

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What is Theseus?

Theseus gives you translucent UI components with blur, refraction, glare, and spring animations – the iOS 26 look, backported to iOS 13+. Same ship, rebuilt plank by plank for older waters.

Why?

Because some of us watched Apple unveil Liquid Glass at WWDC 2025 and quietly wondered if they could drop support for iOS 13. This is for everyone still supporting devices from 2015.

<table> <tr> <td width="25%" align="center"> <img src="assets/tabBar.gif" width="180" alt="TabBar"> <br><strong>TabBar</strong> </td> <td width="25%" align="center"> <img src="assets/slider.gif" width="180" alt="Slider"> <br><strong>Slider</strong> </td> <td width="25%" align="center"> <img src="assets/switch.gif" width="180" alt="Switch"> <br><strong>Switch</strong> </td> <td width="25%" align="center"> <img src="assets/glassView.gif" width="180" alt="Glass View"> <br><strong>Glass View</strong> </td> </tr> </table>

What you get

The iOS 26 Liquid Glass look, running on devices from 2019
Metal GPU rendering (with a sensible fallback for ancient hardware)
Three drop-in components: TabBar, Slider, Switch, GlassView
Accessibility support out of the box
Automatic device adaptation – it won't melt an iPhone 8
Spring-based morphing animations

Installation
Components
Configuration
Advanced

Installation

Add to your Package.swift:

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

Or in Xcode: File → Add Package Dependencies... → paste the repository URL.

| Requirement | Version | |-------------|---------| | iOS | 13.0+ | | Swift | 5.9+ | | Metal | Optional (fallback available) |

Quick Start

import Theseus

let glassView = TheseusView()
glassView.shape.cornerRadius = 20
glassView.sourceView = backgroundView
view.addSubview(glassView)

</td> <td width="50%" align="center">

</td> </tr> </table>

<details> <summary><strong>SwiftUI</strong></summary>

Theseus is a UIKit-based library. For SwiftUI, use UIViewRepresentable wrappers with the Coordinator pattern for proper two-way binding.

Complete, working wrappers are provided in: TheseusDemoSwiftUI/TheseusDemoSwiftUI/Helpers/TheseusViewRepresentable.swift

Includes:

TheseusViewRepresentable – Core glass lens
TheseusTabBarRepresentable – Tab bar with selection binding
TheseusSwitchRepresentable – Toggle with @Binding isOn
TheseusSliderRepresentable – Slider with @Binding value

| Requirement | Version | |-------------|---------| | Library | iOS 13+ | | SwiftUI demo | iOS 15+ |

</details>

Components

Three controls, powered by TheseusView.

TheseusTabBar

The glass capsule floats over your selected tab.

let tabBar = TheseusTabBar()
tabBar.items = [
    TheseusTabBarItem(
        icon: UIImage(systemName: "house"),
        title: "Home"
    ),
    TheseusTabBarItem(
        icon: UIImage(systemName: "magnifyingglass"),
        title: "Search"
    ),
    // ...
]
tabBar.selectedIndex = 0
tabBar.onItemSelected = { index in
    print("Selected tab: \(index)")
}

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</td> </tr> </table>

TheseusSlider

The knob stretches into a glass capsule while you drag, or snaps to positions if you need a stepper.

let slider = TheseusSlider()
slider.minimumValue = 0
slider.maximumValue = 100
slider.setValue(50)

// For discrete positions (like a stepper)
slider.positionsCount = 5
slider.markPositions = true

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</td> </tr> </table>

TheseusSwitch

A toggle that morphs as you flick or drag it.

</td> <td width="50%">

let toggle = TheseusSwitch()
toggle.isOn = true
toggle.onTintColor = .systemGreen
toggle.offTintColor = .systemGray4
toggle.onValueChanged = { isOn in
    print("Switch: \(isOn ? "ON" : "OFF")")
}

</td> </tr> </table>

TheseusView

The core building block. A fully customisable glass lens – use it to build your own components or as a standalone translucent overlay.

let glassView = TheseusView()

// Shape
glassView.shape.cornerRadius = 24
glassView.shape.borderWidth = 1.0

// Glass effect
glassView.blur.radius = 20
glassView.refraction.intensity = 1.2
glassView.refraction.dispersion = 3.0

// Appearance
glassView.opacity = 0.85
glassView.theme.tintColor = .systemBlue
    .withAlphaComponent(0.1)

// Connect to background
glassView.sourceView = backgroundImageView

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</td> </tr> </table>

TheseusView supports:

Blur – Gaussian blur with configurable radius
Refraction – Edge distortion with chromatic dispersion
Edge effects – Fresnel rim glow and specular highlights
Morphing – Spring-based shape animations

Configuration

Basic

var config = TheseusConfiguration()
config.blur.radius = 20
config.shape.cornerRadius = 16
config.opacity = 0.9
config.theme.tintColor = UIColor.systemBlue.withAlphaComponent(0.1)

let glassView = TheseusView(configuration: config)

<details> <summary><strong>Advanced Configuration</strong></summary>

// Refraction (glass distortion)
config.refraction.edgeWidth = 22.0
config.refraction.intensity = 1.45
config.refraction.dispersion = 4.0

// Edge effects (fresnel / highlights)
config.edgeEffects.rimRange = 45.0
config.edgeEffects.rimGlow = 1.0
config.edgeEffects.rimHardness = 12.0

// Glare (light reflection)
config.edgeEffects.glareRange = 450.0
config.edgeEffects.glareIntensity = 1.0
config.edgeEffects.lightAngle = .pi * 0.3
config.edgeEffects.glareFocus = 0.75

// Morphing animation
config.morph.tension = 0.18
config.morph.friction = 0.88
config.morph.smoothing = 0.45

See TheseusConfiguration.swift for all available options.

</details>

Advanced

Device Adaptation

Theseus automatically detects device capabilities and adjusts rendering:

| Tier | RAM / Cores | Example Devices | Rendering | |------|-------------|-----------------|-----------| | Tier 3 | ≥6GB, ≥6 cores | iPhone 12+ | Full Metal + true refraction | | Tier 2 | ≥4GB, ≥6 cores | iPhone 8–11 | Metal, selective refraction | | Tier 1 | ≥3GB | Older iPhones | Metal, cheap approximation | | Tier 0 | <3GB | Very old devices | UIVisualEffectView fallback |

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<details> <summary><strong>Override for Testing</strong></summary>

let settings = TheseusSettings.shared
settings.tierOverride = .tier0
settings.refractionPolicyOverride = .cheapApprox
settings.resetToDefaults()

</details>

</td> </tr> </table>

Accessibility

Theseus respects system settings automatically.

| Setting | Behaviour | |---------|----------| | Reduce Transparency | Solid backgrounds instead of blur | | Reduce Motion | Disables spring morphing animations | | Low Power Mode | Downgrades effects, reduces frame rate |

Performance

Pause rendering when views are hidden to save GPU cycles:

glassView.pauseRendering()
glassView.resumeRendering()

Demo Apps

| Demo | Path | Description | |------|------|-------------| | UIKit | TheseusDemo/ | All components with settings panel | | SwiftUI | TheseusDemoSwiftUI/ | Complete wrappers (iOS 15+) |

License

Apache License 2.0

If you ship Theseus, I'd love a mention in About → Credits.

Package Metadata

Repository: valzevul/theseus

Default branch: master

README: README.md

valzevul/theseus

What is Theseus?

Table of Contents

Installation

Quick Start

Components

TheseusTabBar

TheseusSlider

TheseusSwitch

TheseusView

Configuration

Basic

Advanced

Device Adaptation

Accessibility

Performance

Demo Apps

License

Package Metadata