create-dmg

create-dmg

Create a good-looking DMG for your macOS app in seconds

Imagine you have finished a macOS app, exported it from Xcode, and now want to distribute it to users. The most common way of distributing an app outside the Mac App Store is by putting it in a .dmg file. These are hard to create, especially good-looking ones. You can either pay for a GUI app where you have to customize an existing design or you can run some homebrewed Bash script and you still have to design it. This tool does everything for you, so you can play with your 🐈 instead.

This tool is intentionally opinionated and simple. I'm not interested in adding lots of options.

Install

Ensure you have Node.js 18 or later installed. Then run the following:

npm install --global create-dmg

Usage

$ create-dmg --help

  Usage
    $ create-dmg <app> [destination]

  Options
    --overwrite                  Overwrite existing DMG with the same name
    --no-version-in-filename     Exclude version number from DMG filename
    --identity=<value>           Manually set code signing identity (automatic by default)
    --dmg-title=<value>          Manually set DMG title (must be <=27 characters) [default: App name]
    --no-code-sign               Skip code signing the DMG

  Examples
    $ create-dmg 'Lungo.app'
    $ create-dmg 'Lungo.app' Build/Releases

DMG

The DMG requires macOS 10.13 or later and has the filename App Name 0.0.0.dmg. For example, Lungo 1.0.0.dmg.

It will try to code sign the DMG, but the DMG is still created and fine even if the code signing fails, for example if you don't have a developer certificate. You can use the --no-code-sign flag to skip code signing entirely and prevent exit code failures in CI environments.

Important: Don't forget to notarize your DMG.

Software license agreement

If either license.txt, license.rtf, or sla.r (raw SLAResources file) are present in the same directory as the app, it will be added as a software agreement when opening the image. The image will not be mounted unless the user indicates agreement with the license.

/usr/bin/rez (from Command Line Tools for Xcode) must be installed.

DMG icon

GraphicsMagick is required to create the custom DMG icon that's based on the app icon and the macOS mounted device icon.

Steps using Homebrew

brew install graphicsmagick imagemagick

Icon example

Original icon → DMG icon

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