You cannot use that function because it removes characters which are part of the set from the ends of the string.
Example:
//Produces "ndia"
[@"India(IND)" stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"(IND)"]];
I suggest you use regex to trim.
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\([A-Z]*\\)" options:NULL error:nil];
NSString *trimmedString = [regex stringByReplacingMatchesInString:sample options:0 range:NSMakeRange(0, [sample length]) withTemplate:@""];
The regex assumes you only have capital letters for countries inside parentheses.