Creating a DMG (Disk Image) installer for an application on macOS is a common way to distribute software in a user-friendly format. Below are the steps to create a DMG installer for your application:
This video describes the process carefully:
Steps to Create a DMG Installer on macOS:
1. Prepare Your Application
Ensure your application is fully built and functional (e.g., compiled into a .app bundle).
Place the .app file in a folder (e.g., name it MyAppInstaller) along with any additional files you want to include (like a README, license file, or scripts).
2. Create a Disk Image
Open Disk Utility (found in Applications > Utilities or via Spotlight).
Go to the menu: File > New Image > Blank Image.
Configure the settings in the dialog box:
Save As: Name your DMG (e.g., MyAppInstaller.dmg).
Where: Choose a location to save the DMG (e.g., Desktop).
Name: Give the mounted volume a name (e.g., MyApp).
Size: Set a size large enough to hold your app and extra space for aesthetics (e.g., 50MB or more, depending on your app size).
Format: Choose Mac OS Extended (Journaled).
Encryption: Select none (unless you want a password-protected DMG).
Partitions: Select Single partition - GUID Partition Map.
Image Format: Choose read/write disk image.
Click Save. This creates a blank DMG file.
3. Mount and Customize the Disk Image
Double-click the newly created .dmg file to mount it. A new volume (e.g., MyApp) will appear on your Desktop or in Finder.
Copy your .app file (and any additional files) into the mounted volume.
Optionally, add a background image or customize the appearance:
Create a background image (e.g., 560×400 pixels, PNG format) with instructions like “Drag to Applications”.
Place the image in the mounted volume.
In Finder, right-click in the volume, select Show View Options, and:
Set the background to your image (drag it into the “Picture” section).
Adjust icon size (e.g., 64×64 or 128×128).
Arrange the .app file and other items neatly.
Add a shortcut to the Applications folder:
In Finder, press Command + T to open a new tab, navigate to /Applications, and drag the Applications folder into the DMG volume while holding Option + Command to create an alias.
4. Eject and Finalize the DMG
Eject the mounted volume by dragging it to the Trash (or right-click and select Eject).
Convert the read/write DMG to a compressed, read-only version:
Open Disk Utility again.
Go to File > New Image > Image from Folder.
Select the folder containing your .app (or the mounted DMG content if you prefer), and click Choose.
In the dialog:
Save As: Name the final DMG (e.g., MyAppInstaller-final.dmg).
Where: Choose a save location.
Image Format: Select compressed.
Encryption: Choose none (or add encryption if desired).
Click Save. Disk Utility will create a compressed .dmg file.
5. Test the DMG
Double-click the final .dmg file to mount it.
Verify that it looks as intended (e.g., background image, layout) and that dragging the .app to the Applications alias works.
Test the application after installation to ensure it runs correctly.
6. Distribute the DMG
Share the finalized .dmg file with users via a website, email, or other means.
Optionally, sign the DMG with a Developer ID for Gatekeeper compatibility:
Use the codesign command in Terminal: codesign -f -s "Developer ID" MyAppInstaller-final.dmg
Replace "Developer ID" with your actual Developer ID certificate name (viewable in Keychain Access).
Optional Enhancements
Notarization: If distributing publicly, notarize your app and DMG with Apple to avoid Gatekeeper warnings:
Use xcrun altool or Xcode to submit the DMG for notarization.
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