title: Add a prefix to TextField in SwiftUI
body: <p>I want a ‘+’ Sign in the <strong>Textfield</strong> which cannot be erased. A user should be able to enter values after it and if he presses backspace it should only erase the value he entered. And  when I write any other number it will automatically add a ‘+’ at the beginning of the enter value.</p>
  
  <p><strong>For Example:-</strong>  I want to add country code in the <strong>textfield</strong> so, '+' automatically add in the  beginning  of the field as soon as user start typing a country code.</p>