---
title: laconicman/kapow
framework: Swift Package Catalog
role: article
path: packages/laconicman/kapow
---

# laconicman/kapow

Delightful, physics-driven effects for **UIKit** — a port of

## Direction docs

The authoritative architecture, plan, and debt register live under [`docs/`](docs/): [Design](docs/Design.md) (decisions + rejected alternatives), [Roadmap](docs/Roadmap.md) (Now/Next/Later), [Tech-Debt](docs/Tech-Debt.md) (`KP-#` register), and [API-Coverage](docs/API-Coverage.md) (what of Pow's surface is here, and what isn't). The notes below are a summary; those docs are authoritative.

## The catalog

**Change effects** fire once per call: `shake(rate:)`, `wiggle(rate:)`, `jump(height:)`, `spin(rate:axis:…)`, `shine(duration:)` / `shine(angle:duration:)`, `glow(color:radius:)`, `pulse(shape:color:drawingMode:count:)`, `spray(origin:images:)`, `rise(origin:images:)`, and the haptic/sound `feedback(…)` family.

**Conditional effects** follow a boolean: `pushDown(isActive:)`, `glow(isActive:…)`, `smoke(isActive:…)`, plus `repeating(every:isActive:_:)` to repeat any change effect.

Pow's *transitions* are deliberately not ported — insert/remove choreography is a different lifecycle in UIKit ([Design](docs/Design.md) § Scope).

## Guarantees

- **Never retains your view** or its view controller. A view deallocating mid-effect tears the   effect down; no completion closure can outlive the screen. - **Concurrent effects compose.** Transform effects publish into a per-view compositor, so a shake   during a jump does not clobber either — nor the view's own `transform`. - **Reduce Motion aware.** Motion effects no-op when it's on; the feedback effects are exempt   because they aren't motion. - **Idle-free.** Frame clocks exist only while an effect is live.

## Installation

Swift Package Manager:

```swift .package(path: "../KaPow")        // or the Git URL once published ```

Then `import KaPow`.

## Documentation

API reference is hosted on the [Swift Package Index](https://swiftpackageindex.com/laconicman/KaPow/documentation/kapow), generated from the DocC catalog in `Sources/KaPow/KaPow.docc/` per `.spi.yml`.

To build it locally, target iOS — the package is UIKit-only, so the SwiftPM plugin's default macOS build cannot compile it:

```sh xcodebuild docbuild -scheme KaPow -destination 'generic/platform=iOS' -derivedDataPath .build/docs ```

## Tests

```sh xcodebuild test -scheme KaPow -destination 'platform=iOS Simulator,name=iPhone 17 Pro' ```

The suite is behavioral as well as numeric: every effect is run on a real view through a live `CADisplayLink` and asserted to install, animate, and fully clean up after itself.

## Showcase

**[KaPowShowcase](https://github.com/laconicman/KaPowShowcase)** is the sample app: every effect rendered side by side with its SwiftUI original, driven by one control, so you can see each one move — and see how faithfully it matches Pow — before adopting it.

```sh git clone https://github.com/laconicman/KaPowShowcase.git cd KaPowShowcase && xcodegen generate && open KaPowShowcase.xcodeproj ```

## License

MIT — see [LICENSE](LICENSE). Portions are ported from Pow (MIT, © Emerge Tools, Inc.); its terms are reproduced in [NOTICE](NOTICE), and every ported file carries an attribution header naming its upstream source.

`LICENSE` is kept as the verbatim MIT text with no additions, so automated license detection (GitHub, Swift Package Index) recognises it; the attribution lives in `NOTICE` instead.

## Package Metadata

Repository: laconicman/kapow

Default branch: main

README: README.md