A Minimal Swift Window Script

A tiny script that makes a window on MacOS 🙂
Minimal window script with no title, just a small gray square window in the bottom left corner of the screen

How to run

# --- to run: ----
./minimal       # for the spartan version
./minimal_large # for the nice version
# --- to compile: ----
# it's just wrapping `swiftc minimal.swift -o minimal`


Heavily inspired by little-fbdev-critcl-play I was curious to know if you can draw pixels directly to the MacOS “framebuffer” (short answer: no, there’s no /dev/fb0 on MacOS, long answer: maybe you can make a file that auto-writes to Quartz Display Services or something??? That’s for another time though.) Frustrated with all of that I went down a different rabbit hole: can I, in a small script, make a MacOS window? Without Xcode, without Tk, or SDL …

I stumbled on this great StackOverflow question & got the bones of minimal.swift.

So I copy/pasted that answer into a Swift file on my latop, ran the compile command & got a bunch of errors.

As that StackOverflow question is from 2015, the answer from 2017 (Swift 3), and I’m now writing in 2023 (using Swift 5.7), some things have broken. This comment gets us most of the way there:

I am running Swift 5 and I had to change a couple of things, but it works.

The changes:

Swift 3 Swift 4
NSApplication.shared() NSApplication.shared
NSApplicationActivationPolicy NSApplication.ActivationPolicy
NSTitledWindowMask .titled

But I ran into one more thing …

minimal.swift:18:31: error: 'NSBackingStoreType' has been renamed to 'NSWindow.BackingStoreType'
AppKit.NSBackingStoreType:2:18: note: 'NSBackingStoreType' was obsoleted in Swift 4
public typealias NSBackingStoreType = NSWindow.BackingStoreType
make: *** [Makefile:2: start] Error 1

Okay, so we change NSBackingStoreType to NSWindow & …

A little square, gray window titled minimal with an app title of minimal in the top left

it works!

This made me think … is this the most minimal? How much of this can we remove? Turns out, most of it! Granted, we are throwing away the ability to [⌘ + Q] quit & the app title, but those are just niceties lol

// The smolest Swift script to make a window in Swift 5.7.2:
import Cocoa
let nsapp = NSApplication.shared
let window = NSWindow.init(contentRect:NSMakeRect(0, 0, 200, 200), styleMask:.titled,backing:NSWindow.BackingStoreType.buffered,defer:false)

Minimal window script with no title, just a small gray square window in the bottom left corner of the screen


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