iospharo

A Pharo Smalltalk VM for iOS and macOS, written as a clean C++ interpreter.

Overview

iospharo runs standard Pharo 13 and Pharo 14 images on iOS devices and Mac (via Catalyst). It is a from-scratch interpreter implementation — not a port of the Cog JIT VM — with full support for the Sista V1 bytecode set, FFI with callbacks, and the standard Pharo test suite.

Note: Pharo 12 and earlier use a different class table layout that the VM does not yet handle.

Status

VM core (solid):

• 99.90% test pass rate on Mac Catalyst (13,040 / 13,053)
• 99.55% test pass rate on iOS Simulator
• FFI with callbacks (sigsetjmp/siglongjmp)
• All standard VM plugins built-in (B2D, JPEG, DSA, SSL, etc.)
• Third-party libraries: cairo, freetype, harfbuzz, pixman, libpng, OpenSSL, libssh2, libgit2

GUI (working):

• Metal rendering pipeline — Pharo desktop renders correctly
• Menu bar, world menu, and context menus all functional
• Touch-to-mouse event translation (tap, long-press, two-finger, pinch, drag)
• Hardware keyboard support with modifier keys
• Image library with download, import, and catalog management

Install from the App Store

Available for iPad, iPhone, and Mac:

Download on the App Store

Requirements:

• iPad (5th gen / 2017 or newer) or iPhone (6s / 2015 or newer) or Mac (Apple Silicon or Intel)
• iOS / iPadOS 15.0 or later, macOS 14.0 or later
• ~150 MB free storage (app + image + sources)

Pharo images are downloaded in-app (no separate download needed).

Beta Testing (TestFlight)

There may be a newer pre-release version available via TestFlight:

1. Install TestFlight from the App Store (free, ~30 MB)
2. Open this invite link on your iPad or iPhone: Join the Beta
3. Tap "Accept" then "Install" — the app appears on your home screen

TestFlight builds expire after 90 days but auto-update when new builds are published.

Building

Building needs Xcode 15+, CMake, and a few Homebrew tools. The short version:

scripts/build-libffi.sh
scripts/build-sdl2.sh
scripts/build-third-party.sh
open iospharo.xcodeproj

The full steps, code signing, and the headless Mac development build are in docs/building.md.

Documentation

• Building - prerequisites, xcframework builds, Xcode app, headless dev build
• Architecture - project structure, app/VM layers, startup patches, VM configuration
• Programmer's overview - deeper tour of the VM internals
• Startup system - the Smalltalk patches applied on every launch
• Known issues - current bugs and limitations
• Test results - Pharo test suite results
• Standalone apps - packaging a Pharo image as its own app
• Credits - upstream projects, bundled and linked libraries

Related

Other repos in this collection:

• smalltalk80-2026 — C++17 virtual machine for Smalltalk-80 on macOS, Mac Catalyst, Linux, and Windows. It boots the 1983 Xerox virtual image to the desktop.
• validate_smalltalk_image — Standalone validator and export tool for Spur-format Smalltalk images. It checks the heap, and it writes SHA-256 manifests and reference graphs.
• pharo-headless-test — Headless test runner for Pharo Smalltalk with a fake GUI. It clicks menus, takes screenshots, and runs the SUnit suite without a display. This project extracted it and includes it as a submodule at scripts/pharo-headless-test/.
• soogle — Search engine for Smalltalk source code. It indexes packages and labels each one with its dialect, such as Pharo, Squeak, or GemStone.
• claude-skills — Collection of open source skills for Claude Code. Each skill is a Markdown file in .claude/skills/ that holds reusable knowledge and algorithms.

License

MIT — see LICENSE and THIRD_PARTY_LICENSES.

Credits

iospharo is a clean C++ reimplementation of the architecture defined by the Pharo and Squeak projects, and iospharo bundles or links many upstream libraries. The full list with versions and licenses is in docs/credits.md.

This software is based in part on the work of the Independent JPEG Group.