Grease

An example of building a clojure library for iOS with graalvm native-image.

Built with membrane.

Update - Nov 2024

Grease is in active development and the docs are a bit out of date. For the latest info, check the #graalvm-mobile channel on the Clojurians Slack (join here).

Game of Life Example

See examples/gol

Media

Watch the project in action on the Apropos Clojure Podcast.
Show Notes

Prerequisites

1. Download java's arm64 static libraries built for ios. They can be downloaded using download-deps

$ scripts/download-deps

2. Setup graalvm and make sure your clojure project is graalvm compatible. https://github.com/BrunoBonacci/graalvm-clojure. These examples were tested using https://github.com/gluonhq/graal/releases/tag/gluon-22.1.0.1-Final. Other versions may or may not work.

Make sure GRAALVM_HOME is set and is on your path before starting.

exportJAVA_HOME=<path-to-graalvm>/Contents/Home
export GRAALVM_HOME="$JAVA_HOME"
export PATH=$JAVA_HOME/bin:$PATH

Usage

0. prerequisites
1. Compile your clojure project

$ ./scripts/compile-shared

This can take a while.

2. Open the xcode project in xcode/MobileTest/MobileTest.xcodeproj
3. Select "Any iOS Device(arm64)" or your connected device as the build target. (iOS Simulator not supported yet)
4. Build and run

Membrane Example

An example project that uses membrane for UI can be found under xcode/TestSkia/TestSkia.xcodeproj. It also starts a sci repl that can be used for interactive development. Simply connect to the repl and start hacking! To update the UI, just reset! the main view atom. Example scripts below.

Usage

0. prerequisites
1. Compile ./scripts/compile-membrane
2. Open xcode/TestSkia/TestSkia.xcodeproj
3. Build and run
4. The console will print the IP addresses available. Connect to repl on your device using the IP address and port 23456.
5. Hack away!

Example scripts

Hello World!

(require '[membrane.ui :as ui])
(require '[com.phronemophobic.grease.membrane :refer
           [main-view]])

(def red [1 0 0])

(reset! main-view
        (ui/translate 50 100
                      (ui/with-color red
                        (ui/label "Hello World!"
                                  (ui/font nil 42)))))

Simple Counter

(require '[membrane.ui :as ui])
(require '[com.phronemophobic.grease.membrane :refer
           [main-view]])


(def my-count (atom 0))

(defn counter-view []
  (ui/translate 50 100
                (ui/on
                 :mouse-down
                 (fn [pos]
                   (swap! my-count inc)
                   nil)
                 (ui/label (str "the count "
                                @my-count)
                           (ui/font nil 42)))))


(add-watch my-count ::update-view (fn [k ref old updated]
                                    (reset! main-view (counter-view))))

(reset! my-count 0)

Basic Drawing

(require '[membrane.ui :as ui])
(require '[com.phronemophobic.grease.membrane :refer
           [main-view]])


(def pixels (atom []))

(defn view []
  (ui/on
   :mouse-down
   (fn [pos]
     (swap! pixels conj pos))
   [(ui/rectangle 600 800)
    (into []
          (map (fn [[x y]]
                 (ui/translate x y
                               (ui/with-color [0 0 1 1]
                                 (ui/rectangle 10 10)))))
          @pixels
     )])
  )

(add-watch pixels ::update-view (fn [k ref old updated]
                                  (reset! main-view (view))))

(reset! pixels [])

Example projects

Found in examples/ directory.

examples/ants - Classic ant sim
examples/gol - Game of Life
examples/objc - Objective-c interop
t3tr0s-bare - Tetris
snake - Snake

Notes

The key ingredients for creating binaries for iOS using native-image are:

• static jdk libraries build for iOS
• static native image libraries built for ios (see ./lib/ios-arm64)
• various configs (see ./conf/).

In addition to gluon, there have also been some other forks that have tried to make building the static jdk and native libs easier. See https://graalvm.slack.com/archives/CN9KSFB40/p1714544531823089 on the graalvm slack.

License

Copyright © 2024 Adrian

Distributed under the GPLv2 License. See LICENSE.