pushViewController and presentViewController are not working.

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//self.view.backgroundColor=[UIColor purpleColor];

UIButton *btn=[UIButton buttonWithType:UIButtonTypeRoundedRect];
btn.frame=CGRectMake(60, 200, 140, 40);
[btn setTitle:@"Button" forState:UIControlStateNormal];
[btn addTarget:self action:@selector(buttonAction) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
}

//-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
//    if([segue.identifier isEqualToString:@"segueId"]){
//
//        DetailViewController *detailVC=segue.destinationViewController;
//        detailVC.text=@"Segue Value";
//        detailVC.delegate=self;
//    }
//}

#pragma mark - ChangeLabelTextDelegate

-(void)changeText:(UIViewController *)viewController text:(NSString *)textValue{

self.mainLabel.text=textValue;

}

-(void)buttonAction{

UIStoryboard *storyboard=[UIStoryboard storyboardWithName:@"Main" bundle:nil];
DetailViewController *detailVC=[storyboard instantiateViewControllerWithIdentifier:@"detailView"];
detailVC.text=@"pushViewController";
detailVC.delegate=self;
[self.navigationController pushViewController:detailVC animated:YES];

// Two method.
//[self performSegueWithIdentifier:@"segueId" sender:self];

/* One method.
UIStoryboard *storyboard=[UIStoryboard storyboardWithName:@"Main" bundle:nil];
DetailViewController *detailVC=[storyboard instantiateViewControllerWithIdentifier:@"detailView"];

detailVC.text=@"Hello World!!";

[self presentViewController:detailVC animated:YES completion:^{
NSLog(@"Call Back...");
}];
*/

}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.

}

@end