Swift System Input

A tiny Swift library for retrieving user input from system sources on macOS. Read the user's currently selected text or clipboard contents with a clean, single-call API, plus the accessibility-permission plumbing needed to make it work.

Features

• 🎯 Single-call API — SystemInput.getText() returns the best available text
• 🖱️ Selected text — read the current selection from the frontmost app via the Accessibility API
• 📋 Clipboard access — read the current clipboard string, or copy text to it
• ⌨️ Cursor injection — paste text at the cursor in any app, restoring the clipboard afterwards
• ✅ Inline validation — pass a validator closure to accept text only when it matches
• 🔁 Smart fallback — prefers selected text, falls back to clipboard automatically
• 🔐 Permission helpers — check, request, and deep-link to Accessibility settings
• 🧹 Auto-trimmed — returned text is whitespace-trimmed for you
• 🪶 Zero dependencies — Foundation, AppKit, and ApplicationServices only

Requirements

• macOS 13.0+
• Swift 5.9+
• Xcode 15.0+

Installation

Swift Package Manager

dependencies: [
    .package(url: "https://github.com/arraypress/swift-system-input.git", from: "1.0.0")
]

Usage

Get Text from the Best Source

Tries selected text first, then the clipboard, returning nil if neither is available:

import SystemInput

if let text = SystemInput.getText() {
    process(text)
}

Validate Before Accepting

// Only return the text if it looks like a URL
if let urlString = SystemInput.getText(validator: { $0.hasPrefix("http") }) {
    openURL(urlString)
}

Individual Sources

// Currently selected text in the frontmost app (requires accessibility permission)
if let selection = SystemInput.selectedText {
    process(selection)
}

// Current clipboard string
if let clipboard = SystemInput.clipboard {
    process(clipboard)
}

Write to the Clipboard

SystemInput.copyToClipboard("Hello, world!")

Inject Text at the Cursor

Pastes text into whatever app is focused (via a synthesized ⌘V), then restores the previous clipboard contents so the user's clipboard is left untouched. This is the most portable injection method — it works in Electron, browsers, and native apps where direct Accessibility text insertion is unreliable. Requires Accessibility permission.

guard SystemInput.inject("Hello, world!") else {
    SystemInput.requestAccessibilityPermission()   // not granted yet
    return
}

// Or leave the injected text on the clipboard afterwards:
SystemInput.inject("Hello, world!", restoreClipboard: false)

Accessibility Permission

Reading selected text requires Accessibility permission. (Note: selectedText is not available to sandboxed Mac App Store apps.)

if !SystemInput.hasAccessibilityPermission {
    SystemInput.requestAccessibilityPermission()   // shows the system prompt
    // or take the user straight to the settings pane:
    SystemInput.openAccessibilitySettings()
}

How It Works

selectedText queries the system-wide Accessibility element for the focused UI element, then reads its AXSelectedText. If that attribute is unavailable, it falls back to combining the element's full value with its AXSelectedTextRange to slice out the selection. Clipboard access goes through NSPasteboard.general.

inject(_:) writes the text to the pasteboard, synthesizes a ⌘V keystroke with a private-state CGEventSource, then restores the previous pasteboard contents once the paste has landed — but only if nothing else wrote to the pasteboard in the meantime (tracked via changeCount).

Testing

swift test

Tests cover the text-source fallback logic, validation, clipboard round-trips, and the pasteboard snapshot/restore that backs injection.

License

MIT License — see LICENSE file for details.

Author

Created by David Sherlock (ArrayPress) in 2026.