Can the use of YLProgressBar added on an alert view cause rejection of my app on app store?
It can. Anything can. Apple has its very own weird and obscure revision system which sometimes seems to lack all logic and contradict itself. Thus, the answer to "can XYZ be a reason for rejection" is always "yes, it potentially can be", and the answer to the question "will my app be approved if I don't do ABC for which another app was rejected?" is "maybe not, maybe yes".