Create a new simulator from CLI

2026-03-07

snippets

xcode simulator

Create a new visionOS simulator. Command takes a name, device type, and runtime.

% xcrun simctl create "TestAVP" com.apple.CoreSimulator.SimDeviceType.Apple-Vision-Pro-4K com.apple.CoreSimulator.SimRuntime.xrOS-26-2 
4F8B10C1-90F3-4E91-8A73-AED33CACE123

Curious Case of the Missing Simulators

2026-03-07

devlogs

xcode simulator

In Xcode I recently encountered an issue where all of my simulators disappeared. In Xcode the canvas would only show a preview for the macOS build and I had no option to preview for any other Apple platform.

The “Devices and Simulator” window was completely empty. The target platforms and simulators are listed as installed in Settings->Components screen in Xcode’s settings.

On the command line, we can confirm this by running xcrun simctl list. Here we see that there are no devices available.

Site Update

2026-03-02

devlogs

website general

Site update

  • Removed the terminal Hugo theme.
  • Updated to custom theme
  • Removed projects section. Project updates are now in devlogs
  • Removed downtime section. This was previously hidden and now removed completely. Downtime updates may appear on a dedicated site in the future.
  • Added social section with links to YouTube, Mastodon, and GitHub
  • About page is now hidden. Content from About has been merged with the social page.
  • Support page is now hidden.

Pinned Entities

2026-03-02

snippets

swift realitykit 

import RealityKit

struct PinnedEntityComponent: Component {
    weak var pinnedto: Entity? = nil
    let pinName: String
    var transform: Transform = .identity
}

struct PinnedEntitySystem: System {
    static let query: EntityQuery = .init(where: .has(PinnedEntityComponent.self))
    init(scene: Scene) {
    }
    
    func update(context: SceneUpdateContext) {
        let entities = context.entities(matching: Self.query, updatingSystemWhen: .rendering)
        for entity in entities {
            guard let comp = entity.components[PinnedEntityComponent.self] else {
                continue
            }
            
            //if the entity we are pinned to is no longer available then remove
            //the pinned object from the scene
            guard let pinnedto = comp.pinnedto else {
                entity.removeFromParent()
                continue
            }
            
            guard let pin = pinnedto.pins[comp.pinName] else { continue }
            
            //pin position and orientation can actually be nil so ! is dangerous here
            entity.setPosition(
                pin.position(relativeTo: nil)!
                , relativeTo: nil)
            entity.setOrientation(
                pin.orientation(relativeTo: nil)! * comp.transform.rotation
                , relativeTo: nil)
        }
    }
}

SwiftUI Text Color From Background

2026-02-18

snippets

swift swiftui

Choose a readable Text color automatically based on the background color.

import SwiftUI
extension Color {
    func bestTextColor() -> Color {
        guard let components = self.resolve(in: .init()).cgColor.components else { return .black}
        guard components.count >= 3 else { return .black }
        let red: CGFloat = components[safe: 0]
        let green: CGFloat = components[safe: 1]
        let blue: CGFloat = components[safe: 2]
        
        // Relative luminance approximation for contrast decisions.
        let luminance = (0.299 * red) + (0.587 * green) + (0.114 * blue)
        return luminance > 0.6 ? .black : .white
    }
}

extension Array<CGFloat> {
    subscript(safe index: Int, default: CGFloat = 0) -> CGFloat {
        guard self.count > index else { return `default` }
        return self[index]
    }
}