ScreenshotKit

A Swift package for capturing screenshots of iOS UI — including full-page scrollable content and stable captures that wait for rendering to settle.

Requirements

• iOS 13.0+
• Swift 6.2+

Building

Because this package targets iOS (UIKit-only), pass the iOS Simulator SDK and triple explicitly:

swift build \
  --sdk "$(xcrun --sdk iphonesimulator --show-sdk-path)" \
  --triple arm64-apple-ios16.0-simulator

Or with xcodebuild:

xcodebuild build -scheme ScreenshotKit -destination "generic/platform=iOS Simulator"

Installation

Swift Package Manager

Add ScreenshotKit to your Package.swift:

dependencies: [
    .package(url: "https://github.com/your-org/swift-ScreenshotKit", from: "1.0.0")
]

Or add it in Xcode via File → Add Package Dependencies.

Usage

Capture the largest available screenshot

Automatically captures the full scrollable content if a UIScrollView is present in the top view controller, otherwise falls back to a window snapshot.

import ScreenshotKit

let image = await UIApplication.shared.largestScreenshot(resize: true)

Stable window snapshot

Captures a window snapshot that polls until two consecutive frames match, ensuring animations and async rendering have settled before capturing.

let image = await UIApplication.shared.stableSnapShot()

Stable scroll view snapshot

Captures the full scrollable content of the top view controller's scroll view, waiting for rendering to settle before compositing the full-page image.

let image = await UIApplication.shared.stableScrollViewSnapshot()

Capture a specific scroll view

let image = await myScrollView.stableScrollViewSnapshot()

Basic view snapshot

let image = myView.snapshot(resize: true)

Access the top view controller

let vc = UIApplication.shared.topViewController

Access the key window

let window = UIApplication.shared.firstWindow

Find a subview by type

let scrollView = view.subviewOfType(UIScrollView.self)

Access splash screen images

Retrieves the app's splash screen images from the system's SplashBoard cache. Returns an empty array if unavailable.

let splashImages = UIApplication.shared.splashScreens

How stable capture works

The stableSnapShot() and stableScrollViewSnapshot() methods use a polling strategy:

1. Capture two consecutive screenshots with a 100ms delay between them.
2. Compare their PNG data.
3. If they differ, wait another 100ms and capture again.
4. Repeat up to 6 times until two consecutive captures match.

This ensures the UI has finished rendering (including async image loads, animations, etc.) before the final screenshot is taken.

Scroll view capture

UIScrollView.stableScrollViewSnapshot() composes a full-page image of the entire scrollable content by:

1. Waiting for stable rendering (polling loop above).
2. Temporarily zeroing out content insets and offsets.
3. Iterating through vertical offsets equal to the viewport height.
4. Drawing each visible section into a CGContext with the correct translation.
5. Restoring original insets and offset via defer.

The resulting image always uses a scale of 1.0 (device-independent pixels) for predictable output dimensions.

API Reference

UIApplication

API	Description
firstWindow: UIWindow?	The key window from the first connected window scene.
topViewController: UIViewController?	The topmost presented view controller, traversing nav, tab, and modal stacks.
topViewController(base:)	Recursive helper for traversing the view controller hierarchy.
largestScreenshot(resize:) async -> UIImage?	Best-effort screenshot: full scroll view content or window snapshot. iOS 16+.
stableSnapShot() async -> UIImage?	Window snapshot that waits for rendering to settle.
stableScrollViewSnapshot() async -> UIImage?	Full-page scroll view capture that waits for rendering to settle.
splashScreens: [UIImage]	Splash screen images from the system SplashBoard cache.

UIScrollView

API	Description
stableScrollViewSnapshot() async -> UIImage?	Full-page capture of scrollable content, polling until stable.

UIView

API	Description
snapshot(resize:) -> UIImage?	Snapshot of the view and its subview hierarchy.
subviewOfType<T>(_:) -> T?	Recursive depth-first search for a subview of a given type.

License

MIT