Step 2 doesn&#x27;t happen. The private API scan is superficial and basically only catches accidental use (for example, maybe somebody discovered the API in a StackOverflow post and didn&#x27;t realize it was private). It doesn&#x27;t catch use that people deliberately want to get through. Getting through the check is as easy as some string obfuscation and a dynamic symbol lookup.<p>If a given private API is a security problem (and I agree that altering the screen&#x27;s gamma settings system-wide may well qualify) then that private API needs to be <i>actually secured</i>, by taking it out of process and gating it on a sandbox entitlement.<p>The private API check is done to allow Apple the flexibility to change those APIs without potentially breaking a ton of apps and pissing off their users. It does nothing whatsoever for security, unless your threat model is programmers capable of writing malware but incapable of obfuscating function calls.