is Manual Referencing Count in Objective C vulnerable to buffer overflow attacks ? or is non ARC applications vulnerable to bufferOverflow attacks?

Reg : CVE-2021-42574 :: How to check my Objective C & Swift code is having any BiDi character ? Like Java can we change our compilation encoding in Xcode & identify the issue areas ?

Any update from Apple on CVE-2021-42574 fix ?

What is Xcode's default compilation Encoding ? How to change it?