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

Question

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.

Please have look this question https://stackoverflow.com/questions/51416391/how-to-create-multiple-y-axis-line-chart-in-danielgindi-ios-chart?noredirect=1#comment89804032_51416391 — Saurabh Jain, Jul 23 '18 at 09:00
@SaurabhJain hmm I have checked his question, and I have used this lib in my past project. In my project only 2 y-axis were there :) — Monika Patel, Jul 23 '18 at 09:23
@SaurabhJain https://stackoverflow.com/questions/51552429/draw-line-on-image-by-handgetsture-in-objective-c check this question — Monika Patel, Jul 27 '18 at 08:38

score 3 · Accepted Answer · answered Jul 23 '18 at 05:25

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

score 0 · Answer 2 · answered Aug 24 '21 at 03:58

For iOS 13 and up change the setupExternalScreen method to this

source : https://stackoverflow.com/a/61474635/9777391

-(void)setupExternalScreen:(UIScreen *)screen shouldRecurse:(bool)recurse {
    
    UIWindowScene* matchingWindowScene = nil;
    
    // For iOS13 and up find matching UIWindowScene
    for(UIScene *aScene in UIApplication.sharedApplication.connectedScenes){
        UIWindowScene *windowScene = (UIWindowScene*)aScene;
        // Look for UIWindowScene that has matching screen
        if (windowScene.screen == screen) {
            matchingWindowScene = windowScene;
            break;
        }
    }
    
    if (matchingWindowScene == nil) {
        // UIWindowScene has not been created by iOS rendered yet
        // Lets recall self after delay of two seconds
        if (recurse) {
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 2 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
                [self setupExternalScreen:screen shouldRecurse:NO];
            });
        }
        // Dont proceed further if none found
        return;
    }
    
    // Instantiate view controller
    ExternalScreenViewController *vc = [[self storyboard] instantiateViewControllerWithIdentifier:@"ExternalScreen"];
    
    // Setup external window
    externalWindow = [[UIWindow alloc] initWithFrame:screen.bounds];
    [externalWindow setRootViewController: vc];

    // Set scene
    [externalWindow setWindowScene:matchingWindowScene];
    // Show the window.
    [externalWindow setHidden:NO];
}

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

2 Answers2