Returning to the root view controller

Question

I am writing a turn-based game for the iOS platform. The client communicates with a remote server using the CocoaAsyncSocket API. Right now I work on this case: the client has been inactive for a while, and has been disconnected from the server due to timeout. If that's the case, I wish to pop back to the login view when the app enters the foreground, to let the user log back in again.

I assume I have to do this kind of work in the -(void)applicationWillEnterForeground of my app's delegate. Checking whether I'm connected or not is not a problem, but I don't know how to dismiss every presenting view controller to take me back to the root view (which happens to be the login view).

My view controllers are presented modally, but I also have two navigation controllers with table views including push segues.

Any help with this problem is highly appreciated. Thanks in advance!

Answer 1

The jarring way to do it is just replace the rootViewController with a new login view controller.

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    if ([self isDisconnected]) {
        self.window.rootViewController = [MyLoginController new];
    }
}

For storyboards, assuming your initial storyboard is the login storyboard.

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    if ([self isDisconnected]) {
        UIStoryboard *storyboard = self.window.rootViewController.storyboard
        self.window.rootViewController = [storyboard instantiateInitialViewController];
    }
}

Depending on your UX, this may or may not be appropriate.

Answer 2

If all of your content views are presented modally from the root view controller (which doesn't sound like a great idea) then from the app delegate (indeed in applicationWillEnterForeground),

// if we need to login
UIViewController *rootViewController = self.window.rootViewController;
[rootViewController dismissViewControllerAnimated:YES completion:nil];

If the root view controller isn't presenting modally then you need to dismiss in the appropriate way. If any other 'child' view controller is presenting modally then it should dismiss. I guess dismissing when that view controller changes parent view controller will work. You may need to add a notification to inform all view controllers that everything is being torn down.