TweakIt

Adjust anything at runtime. Ship nothing to production.

TweakIt is a spiritual successor to SwiftTweaks — the beloved library that let you fine-tune your app without recompiling. TweakIt brings that same magic to modern SwiftUI with a declarative DSL, real-time editing, and zero production overhead.

     

Why?

Because recompiling to change an animation duration by 0.05 seconds is a crime against your time.

TweakIt lets you define tweakable parameters once and get a full debug panel for free. Drag sliders, flip toggles, pick options — see changes instantly without a rebuild.

Features

• Declarative DSL — Define tweaks with result builders. Types infer the controls automatically.
• Real-time editing — Sliders, toggles, text fields, pickers, steppers, and action buttons.
• Swipe to reset — Changed a value? Swipe any row to snap it back to its default.
• Modification tracking — Orange dots show what you've changed at a glance.
• Custom tabs — Add your own SwiftUI views alongside the built-in tweaks browser.
• Floating button + gesture — Tap the button or two-finger double-tap anywhere to open.
• Section master toggles — Enable/disable entire feature flag groups with one switch.
• Release-safe by default — When disabled, all APIs no-op and TweakRef returns defaults directly. Active in DEBUG builds automatically, or opt-in for any build config with one line: TweakIt.isEnabled = true.

Quick Start

1. Define your tweaks

import TweakIt

enum AppTweaks {
    static let store = TweakStore {
        TweakCategory("Animations", icon: "sparkles") {
            TweakSection("Spring") {
                TweakDefinition("duration", default: 0.46, range: 0.1...2.0)
                TweakDefinition("damping", default: 0.8, range: 0.1...1.0)
            }
        }
        TweakCategory("Debug", icon: "ladybug") {
            TweakSection("Network") {
                TweakDefinition("mockMode", default: false)
                TweakDefinition("endpoint", default: "production",
                                options: ["production", "staging", "local"])
            }
        }
    }
}

2. Install the panel

#if DEBUG
TweakPanel.install(store: AppTweaks.store)
#endif

Internal/TestFlight builds: Set TweakIt.isEnabled = true before calling install() to enable tweaks in any build config. This works regardless of SPM limitations — no special compiler flags needed on the package itself.

3. Read values

let duration: CGFloat = AppTweaks.store["Animations.Spring.duration"]

That's it. The panel appears via a floating button or two-finger double-tap.

Control Types

The control is inferred from your default value and parameters:

Definition	Control
TweakDefinition("flag", default: true)	Toggle
TweakDefinition("speed", default: 0.5, range: 0.0...1.0)	Slider
TweakDefinition("columns", default: 3)	Stepper
TweakDefinition("columns", default: 3, range: 1...10)	Integer slider
TweakDefinition("name", default: "hello")	Text field
TweakDefinition("env", default: "prod", options: ["prod", "staging"])	Picker
TweakDefinition("reset", action: { ... })	Action button

Action buttons don't store a value — they fire a closure on tap. Great for debug shortcuts like resetting state or clearing caches.

TweakRef — Typed Handles

For ergonomic access, TweakRef gives you a typed handle with modification tracking:

static let duration: TweakRef<CGFloat> = store.ref("Animations.Spring.duration")

// Read/write:
AppTweaks.duration.value        // 0.46
AppTweaks.duration.value = 0.5
AppTweaks.duration.isModified   // true
AppTweaks.duration.reset()      // back to 0.46

In release builds, .value returns the compile-time default directly — zero overhead.

Custom Tabs

Add your own panels alongside the built-in tweaks browser:

TweakPanel.install(
    store: AppTweaks.store,
    tabs: [
        TweakTab("Actions", icon: "bolt") { ActionsView() },
        TweakTab("Stats", icon: "chart.bar") { StatsView() },
    ]
)

Shake to Toggle

By default, shaking the device toggles the floating button's visibility. This uses method swizzling on UIWindow.motionEnded(_:with:) (scoped to UIWindow only, debug builds only).

If you prefer to avoid swizzling, disable it and trigger the button yourself:

TweakPanel.install(store: AppTweaks.store, shakeToToggleButton: false)

You can then toggle the button programmatically via TweakPanel.buttonState:

// In your own shake handler or gesture recognizer:
TweakPanel.buttonState?.toggle()

Installation

Swift Package Manager:

https://github.com/warpling/TweakIt.git

iOS 16+ · Swift 5.9+ · Zero dependencies

Acknowledgments

TweakIt is a spiritual successor to SwiftTweaks by Bryan Clark, which pioneered the idea of runtime-tweakable parameters for iOS. SwiftTweaks was a joy to use and a huge inspiration — TweakIt aims to carry that torch forward with a modern Swift DSL and SwiftUI.

License

MIT. See LICENSE for details.