[iOS] Return to Home Screen after a guest powers off

[conath]

Whenever a guest VM is powered off in UTM on iOS, the app exits to the home screen. This impractical for several reasons:

• it looks to the user as if UTM has crashed when it has in fact exited without error
• need to relaunch the app every time to test different VM configuration
• limits use of UTM in Split View because UTM exiting causes iPadOS to go back to the home screen
• the app still appears in the app switcher despite it actually not running anymore (least important point)

The very first of these points can be addressed by calling [UIApplication suspend] instead of exit(0). This results in a graceful animation to the Home Screen. UTM may then call exit(0) when in the background.

Code example from StackOverflow:

-(void)doExit
{
        // animate to home screen
        UIApplication *app = [UIApplication sharedApplication];
        [app performSelector:@selector(suspend)];

        // wait 2 seconds while app is going background
        [NSThread sleepForTimeInterval:2.0];

        // exit app when app is in background
        exit(0);
    }
}

Resolving the issue entirely, meaning returning to the VM list after the VM powers down, seems more challenging to implement. Currently when a VM is started, a new ViewController takes over the key UIWindow and (as far as I can tell) no reference is kept to the VM list view.

So to implement going back either a NavigationController of sorts must be introduced to be able to navigate back, or the VM list view must be re-created after the VM powers down and a new UIWindow created that shows the list.

[osy]

Due to #6 there's no way to start a second VM in the same address space. But I can try to implement the graceful exit.