You can search arrays using predicates, for example:
NSMutableArray* names = [NSMutableArray arrayWithObjects:@"Andy", @"Bart", @"Bob", nil];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"SELF beginswith[c] 'b'"];
NSArray* namesStartingWithB = [names filteredArrayUsingPredicate: predicate];
NSArray NSPredicate . , XML (, RSS-), Matt Gallagher libxml2 XML XPath Cocoa.