A Swift Package for simulating color blindness in iOS apps. Uses GPU-accelerated color transformation for real-time, full frame rate simulation.

• iOS 17+
• Swift 5.9+

Add Colorblinds to your project via Swift Package Manager:

https://github.com/jdekock/Colorblinds

Or add it to your Package.swift:

dependencies: [
    .package(url: "https://github.com/jdekock/Colorblinds", from: "2.0.0")
]

Normal	Picker	Tritanopia	Achromatopsia

Apply a specific simulation:

import Colorblinds

struct ContentView: View {
    var body: some View {
        MyAppView()
            .colorBlindSimulation(.deuteranopia)
    }
}

Bind to an optional type (nil removes the filter):

@State private var selectedType: ColorBlindType?

var body: some View {
    MyAppView()
        .colorBlindSimulation(selectedType)
}

Full simulator experience — triple-tap anywhere to open a picker sheet:

var body: some View {
    MyAppView()
        .colorBlindSimulator()
}

Note: Apply the modifier to your content views rather than to a NavigationStack or TabView. These container views use internal rendering (e.g. navigation bar materials) that conflicts with the Metal shader, resulting in a yellow warning screen.

Full simulator experience — call start with your app's window, then triple-tap to open a picker:

import Colorblinds

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options: UIScene.ConnectionOptions) {
    guard let windowScene = scene as? UIWindowScene,
          let window = windowScene.windows.first else { return }

    ColorBlindOverlay.shared.start(in: window)
}

Direct control:

// Apply a specific simulation
ColorBlindOverlay.shared.simulate(.protanopia, in: window)

// Remove the simulation
ColorBlindOverlay.shared.stop()

• SwiftUI — Uses a [[stitchable]] Metal shader via .colorEffect(), running directly in SwiftUI's render pipeline. No screen capture, no overlay. Truly live at full frame rate.
• UIKit — Uses CADisplayLink to capture the window's layer, applies a CIColorMatrix filter on the GPU, and renders the result to an MTKView overlay.

MIT