A DMG Installer is convenient way to provide end-users a simple way to install an application bundle. They are basically a folder with a shortcut to the Applications directory but they can be customized with icons, backgrounds, and layout properties. A DMG file (.dmg) is a Mac OS X Disk Image file and it is used to package files or folders providing compression, encryption, and read-only to the package.
##Creating the DMG file
#Disk Utility
Type Disk Utility into Spotlite CMD+SPACEBAR from Finder
or from Terminal:
open /Applications/Utilities/Disk\ Utility.app/
File -> New -> Disk Image from Folder or CMD+SHIFT+N
Select the folder myapp.app/ when prompted then click Image.
In the Save As field enter a name for the file like myapp.dmg.
From the Image Format drop-down select read/write then click Save.
#Edit Folder Preferences Mount the dmg and open it by double-clicking the file in Finder or from Terminal:
open myapp.dmg
open /Volumes/myapp/
Create a link/shortcut to /Applications folder by right-clicking
on the Applications folder and selecting Make Alias then drag it into
the dmg folder or from Terminal:
cd /Volumes/myapp/
ln -s /Applications Applications
In Finder press CMD+1 to switch to icon view and arrange icons as needed.
Press CMD+J to show the View Options window and adjust view settings as needed.
From Background: section choose Picture then
Drag and drop the image you want to use as the
background where it says Drag image here.
Unmount/Eject the dmg when finished with View Options or from Terminal:
umount /Volumes/myapp/
#Compress and convert to Read-only
From Disk Utility right-click on myapp.dmg disk image and
select Convert "myapp.dmg".
In the Save As field enter a new name for the file like myappfinal.dmg.
From the Image Formate drop-down select read-only then click Save
or from Terminal:
hdiutil convert -format UDZO -o myappfinal.dmg myapp.dmg
#FIN Congratulations you are finished! Mount the new dmg to verify it is working properly.
For anyone who, like me, completely failed to make any of these guides work. Here is a concise step-by-step guide for macOS 26:
Create a new folder. Place your app inside it, along with an alias to the Applications folder.
Open Disk Utility. Go to File > New Image > Image from Folder (or use the shortcut Cmd + Shift + N).
Select the folder from Step 1 as the source. Under "Image Format," choose "Sparse Bundle Image". Save the image.
Mount the image by double-clicking it. It will appear under "Locations" in Finder, navigate to it there.
Inside the mounted image, press Cmd + J to open the view options. Customize the icon order, size, background, etc.
Once customized, eject the image.
Open Disk Utility again. Go to Images > Convert, select the image created in Step 3.
In the conversion options, under "Image Format," select a .dmg format, e.g., the default option. Click Convert and save the dmg.
Done!
To set a background picture: Create a hidden folder (e.g., ".background") inside the mounted image from step 4. Place your background picture in that hidden folder, then in the view options, select the picture from the hidden folder as the background.