This is, of course, a gross generalization but, you don't want to work anywhere that will hire you based on a certification. Instead, you should write code that you can demonstrate to and discuss with an interviewer to affirm to them your knowledge of Objective-C, Cocoa, Cocoa Touch, etc.
Certifications show that you were able to memorize and regurgitate some syntax, maybe design patterns, etc. which you may have promptly forgotten. Being able cram stuff into your head then dump it onto paper/a computer doesn't qualify you for a job, unless the job is taking tests. Having experience using the skills these tests are
supposed to measure is far more important.
To more directly answer your question: No. Apple does not offer certifications for OS X or iPhone programming. Even if they did, you don't want or need it.
-Lee
EDIT: This thread was almost identical to yours, and got pretty similar responses:
https://forums.macrumors.com/threads/747972/
