Arabic keyboard missing 'ذ' and 'ّ' on Mac OS X

 I suffered from Arabic keyboard on my Mac because of the missing key 'ذ' and 'ّ'.
But I found the solution from this website.

https://github.com/andrewheiss/Fixed-Arabic-PC-for-OS-X

The following content is from the above website.
I appreciate the author Andrewheiss.

download the key layout files

README.md

Fixed Arabic - PC keyboard layout for OS X

For some reason, the "Arabic - PC" keyboard layout in Mac OS X 10.4 and above is missing the letter thal ( ذ ) and the diacritic shadda ( ّ ). On standard Arabic PC keyboard layouts these are assigned to the tilde key to the left of the number 1, but OS X replaced the key with a comma.

Install this keyboard layout to restore the missing thal and shadda.

Installation

1. Copy both Arabic-PC-fixed.keylayout and Arabic-PC-fixed.icns to /Library/Keyboard Layouts or ~/Library/Keyboard Layouts
2. Go to System Preferences > Language & Text > Input Sources.
3. At the bottom of the list of keyboard layouts you should see one titled "العربي".
4. Select it and type away!