Have you read the Parse docs for PFQuery?
Assuming each PFUser has an attribute like phoneNumber
, something like:
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"phoneNumber in %@", phoneNumbersArray];
PFQuery *query = [PFQuery queryWithClassName:[PFUser parseClassName] predicate:predicate];
NSArray *pfUsers = [query findObjects];
There shouldn't be much more too it, unless you've changed something else, such as making PFUser rows not readable by others via ACL.