📦 Eraser

A small iOS library that provides a mask-based erase/draw view over one or two images. Use your finger or a stylus to erase (reveal the bottom image) or draw (restore the top image) with undo/redo support.

Requirements

• iOS 13+
• Swift 5.9+
• Xcode 15+

Installation

Swift Package Manager

Add the Eraser package to your project:

1. In Xcode: File → Add Package Dependencies…
2. Enter the repository URL (or add a local path to this package).
3. Add the Eraser library to your app target.

Or add to your Package.swift:

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

Usage

Two-layer (before / after)

Typical use: put after on top of before; erase reveals the bottom image, draw restores the top image on the same paths.

1. Create an EraserView and add it to your view hierarchy.
2. Set lineWidth (brush size) and mode: .erase or .draw.
3. Call configure(foreground:afterImage, background:beforeImage).
4. Optionally set onUndoRedoStateChanged to enable/disable undo/redo buttons.

import Eraser

let eraserView = EraserView(frame: view.bounds)
view.addSubview(eraserView)

eraserView.lineWidth = 24
eraserView.mode = .erase
eraserView.onUndoRedoStateChanged = { canUndo, canRedo in
    undoButton.isEnabled = canUndo
    redoButton.isEnabled = canRedo
}
eraserView.configure(foreground: afterImage, background: beforeImage)

• Mode .erase — strokes reveal the before (bottom) image.
• Mode .draw — strokes bring back the after (top) image on those paths.

Single image

Use configure(with: image) for a single image; erase/draw then affect that image with the view’s background showing where erased.

eraserView.configure(with: myImage)

Undo / Redo / Reset

• eraserView.undo() — undo last stroke
• eraserView.redo() — redo last undone stroke
• eraserView.resetToMask() — clear all strokes and reset

Change image

• eraserView.changeSource(for: anotherImage) — replace the foreground (and optional background) and reinitialize.

Demo

This repository includes an EraserDemo iOS app in the Demo/ folder. Open Demo/EraserDemo.xcodeproj in Xcode (the Eraser package is linked as a local dependency), then run the EraserDemo scheme on a simulator or device. The demo uses before and after assets: the toolbar has mode (Erase / Draw), brush size, Undo, Redo, and Reset.

License

See the repository license file.