How To Display Custom Content On A External Screen From A iOS Device

I have created one application in Objective C. I want to implement functionality for showing selected content area of the screen on external display. For example, I have total 10 screens and I want to show 4 screens and don't want to show entire portion of the screen, just want to show selected view and area of the screen in external display.

I have done research on this, I found one tutorial, but that tutorial is available in swift language and I want to implement this things in objective c language.

The Swift tutorial in Objective C Code:

#import "ViewController.h"
#import "ExternalScreenViewController.h"

@interface ViewController ()
{
    UIWindow *externalWindow;
    UIWebView *webView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    webView = [[UIWebView alloc] init];
    [self setupScreenNotifications];
    NSURL *url = [NSURL URLWithString:@"http://www.spazstik-software.com"];
    NSURLRequest *req = [NSURLRequest requestWithURL:url];
    [webView loadRequest:req];

    if ([[UIScreen screens] count] > 1) {
        [self setupExternalScreen:[UIScreen screens][1]];
    }
}


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

-(void)setupScreenNotifications {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(externalScreenDidConnect:) name:UIScreenDidConnectNotification object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(externalScreenDidDisconnect:) name:UIScreenDidDisconnectNotification object:nil];

}

-(void)externalScreenDidConnect:(NSNotification *)notification {
    UIScreen *screen = (UIScreen *)[notification object];
    if (screen != nil) {
        [self setupExternalScreen:screen];
    }
}

-(void)externalScreenDidDisconnect:(NSNotification *)notification {
    id obj = [notification object];
    if (obj != nil) {
        [self teardownExternalScreen];
    }
}

-(void)setupExternalScreen:(UIScreen *)screen {
    ExternalScreenViewController *vc = [[self storyboard] instantiateViewControllerWithIdentifier:@"ExternalScreen"];
    externalWindow = [[UIWindow alloc]initWithFrame:screen.bounds];
    externalWindow.rootViewController = vc;
    externalWindow.screen = screen;
    externalWindow.hidden = false;
}

-(void)teardownExternalScreen {
    if (externalWindow != nil) {
        externalWindow.hidden = true;
        externalWindow = nil;
    }
}
@end