How to a share link in twitter with out set up in iphone settings page?

i want to share a link in twitter. At the time click on twitter button share a link.But first time click on twitter button i want to show twitter login to share in that page only no need to go in iphone settings page

My code is

UIButton *twitterBtn=[[UIButton alloc]initWithFrame:CGRectMake(50,100, 50,  50)];   
[twitterBtn setImage:[UIImage imageNamed:@"Twitter-icon.png"] forState:UIControlStateNormal];
[twitterBtn addTarget:self action:@selector(twitterBtnClicked:) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:twitterBtn];

-(void)twitterBtnClicked:(UIButton *)sender
{
    NSString *link=@"http://myWebpage.com";
    TWTRComposer *composer = [[TWTRComposer alloc] init];
    [composer setText:[NSString stringWithFormat:@"%@,%@ ....",      [itemDetailsDict objectForKey:@"name"],link]];

    [composer setImage:[UIImage imageNamed:@"fabric"]];
    [composer showWithCompletion:^(TWTRComposerResult result) {

        if (result == TWTRComposerResultCancelled) {
            NSLog(@"Tweet composition cancelled");
        }

        else {
            NSLog(@"Sending Tweet!");
        }
    }];
}