Turkish character with standard french keyboard

Thank you Tom, your last post and first suggested link resumes what I was looking for, in particular the first comment

https://apple.stackexchange.com/questions/20505/how-to-add-characters-to-the-press-and-hold-character-picker-in-os-x-lion?noredirect=1&lq=1

I've read then tried different methods described above and the one which seems to work more or less is shown in this post

https://apple.stackexchange.com/a/301869

To keep a record of what I've just done on my iMac and my MacBook Air (both running with Mojave 10.14.6), here are the different steps I've followed:

Go to: /System/Library/Input Methods/PressAndHold.app

—> Right Click + Show Package Contents

/Contents/PlugIns/PAH_Extension.appex

—> Right Click + Show Package Contents

/Contents/Resources/Keyboard-en.plist then /Contents/Resources/Keyboard-fr.plist

I've made a copy of both the english one and the french one then launched Xcode to check their content. Now the bad news or confirmation that Apple has never incorporaed neither in English or French keyboard the complete turkish alphabet (the G and C are missing, the I and S are partial, only the U and the O are found). I do speak spanish, portuguese, french, english and some turkish so it seems Apple have incorporated alphabet from germany and other european language which do use say ü or ö which are found in german.

Now maybe there is a way to add in the Xcode view shown before the missing roman letters (G, C) and complete the missing information (I and S) to quickly access any turkish alphabet.

It is very strange Apple chose to ignore turkish because for example on my Samsung mobile phone, it is all there so I guess Apple would need to reconstruct many plist files since Mojave. I do not possess an iPhone so cannot check the the missing turkish letters is an issue as well.

Albert

Ok it has been done quite easy using Xcode, here I've added missing I's (turkish with not dot) then created special cases of turkish G's and S's (upper and lower case). As a reminder the C's, O's and U's do exists from other roman language so can be re-used by Turkish language.

However I can't update or change the root file, my new updated document Keyboard-fr.plist is on my desk. What safe and quick method do you recommend to disable the root files protection ?

Another question, it seems some letters will choose RIGHT and others LEFT, what is the rationale or definition since I did create 2 new items (G's and S's) ?

Hello Tom, well wether on my iMac or my MacBook Air both running with Mojave, I did active both French and Turkish keyboard son I can toogle. However my question is about another very useful feature which partially work on Apple and fully on Samsung.

If you keep say french keyboard or US keyboard, then you press character U and wait, it will pop up after say 1s or 2s many different U's variant from different languages then you select which one. With Turkish, some letters will never appear, some other will appear whereas with my Samsung smartphone, it covers all languages related to the given letter.

I can try to make screenhot if not clear, otherwise try press letter u then wait, you'll see different types of u's. The turkish ü or ö or ç will work but the turkish i or g or s will not work.

Well it has been a long time I've not used Xcode, I'll try later or tomorrow to see if I can add the Turkish characters which are missing. Again thank you for the guidance, will keep informed. Bye from Toulouse (France)

Ok just done via special boot Terminal then csrutil... it all work, thanks again Tom

Bonne journée, Albert