How to get character entered on keydown event in WPF C#

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C#

WPF

keyboard

Hello

I'm using wpf c# in visual studio i want to prevent user can enter Arabic character , Just Persian Character

like when user entered this value on keyboard → "ي" change it to "ی"

my means something like this : when user press button to type "A" on keyboard i want to change this character, first check if is "A" change to "B"

i did it in Windows Form Application , but that code does not work in WPF

My Code in Windows From :

if (e.KeyChar.ToString() == "ي")
            {
                e.KeyChar = Convert.ToChar("ی");
            }

My Code in WPF :

if (e.Key.ToString() == "ي")
    {
         e.Key.ToString("ی");
     }

These codes not working in WPF

Please Help

What I have tried:

if (e.KeyChar.ToString() == "ي")
            {
                e.KeyChar = Convert.ToChar("ی");
            }

i test this in wpf but did't work