Use Regular Expression (?i)
instead ! credit goes to https://stackoverflow.com/a/9655203/2398886 , https://stackoverflow.com/a/9655186/2398886 and http://www.regular-expressions.info/modifiers.html
So replace
[query whereKey:@"Number" containsString:searchTerm];
with
[query whereKey:@"Number" matchesRegex:[NSString stringWithFormat:@"(?i)%@",searchTerm]];
or you can also use
[query whereKey:@"Number" matchesRegex:searchTerm modifiers:@"i"];
Your final code should be :
PFQuery *query = [PFQuery queryWithClassName: @"Firefacts"];
[query whereKeyExists:@"Number"];
[query whereKey:@"Number" matchesRegex:searchTerm modifiers:@"i"];