if just want to increase the size of NSSearchfield then u did not need to subclass it you just define NSSearchfield programetically and give ur desire size during defining of frame.
example is given below
mySearchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0,44,320,70)]; mySearchBar.autocorrectionType = UITextAutocorrectionTypeNo; mySearchBar.autocapitalizationType = UITextAutocapitalizationTypeNone; mySearchBar.showsCancelButton = NO; mySearchBar.delegate=self; [self.view addSubview:mySearchBar];
or if you want some diffrent look specify it i may help you