使用 rangeOfString 搜索整个字符串

 for(NSString * strUserName in arrUserInfo )
{
  NSRange range = [strUserName rangeOfString:searchText options:(NSCaseInsensitiveSearch|NSDiacriticInsensitiveSearch)];
  if (range.length > 0)
  {
    [self.arrSearhResults addObject:strUserName];
  }
}