Check and open Twitter URL Scheme

gistfile1.m

            NSString *str = [NSString stringWithFormat:@"twitter://user?screen_name=%@", bstr];
            if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:str]]) {
                [[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];
            }else {
                UIAlertView*alert = [[UIAlertView alloc] initWithTitle:@"Tweetoverview" message:NSLocalizedString(@"Can not open twitter app. Please install twitter app to send tweet.", @"Can not open twitter app. Please install twitter app to send tweet.") delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                [alert show];
            }