Question

My universal app is a single full screen view. Pressing a button flips to reveal a settings page:

- (void) showSettings
{
FlipsideViewController * flipsideVC = [FlipsideViewController alloc];

NSString * settingsNib;
if ( isIPad() )
    settingsNib = isCurrentlyPortrait() ? @"settings_iPad_portrait" : @"settings_iPad_landscape";
else
     settingsNib = @"settings_iPhone";

[flipsideVC initWithNibName: settingsNib
                     bundle: nil ];

flipsideVC.delegatePointingToMainVC = self;

flipsideVC.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;

[self presentModalViewController: flipsideVC 
                        animated: YES ];

[flipsideVC release];
}

and the settings page invokes the delegate method: I recreate the main view in light of the changed settings, and flip back.

- (void) settingsDidQuit:(FlipsideViewController *) flipsideVC 
{
[self createOrRecreateWheelView];
[self dismissModalViewControllerAnimated: YES];
}

But what if the user rotates the iPad on the settings page? Apple decrees that my app must handle this. But how to do this? can I dynamically load a new XIB for the settings page?

I can’t see a way to do that, so my attempted solution is to catch the rotation within the settings view, …

- (void) didRotateFromInterfaceOrientation: (UIInterfaceOrientation) oldInterfaceOrientation 
{
[self.delegatePointingToMainVC settingsOrientationChanged]; 
}

…and call back to the main view controller, which dissolves the settings view controller and recreates it in light of the current orientation.

- (void) settingsOrientationChanged
{
[self dismissModalViewControllerAnimated: YES];
[self showSettings];
}

There is a trivial problem straight away — didRotateFromInterfaceOrientation gets triggered automatically when the settings page loads. I can prevent this by setting a boolean to false in init, and modifying thus:

- (void) didRotateFromInterfaceOrientation: (UIInterfaceOrientation) oldInterfaceOrientation 
{
if (initialized)
    [self.delegatePointingToMainVC settingsOrientationChanged]; 

initialized = true;
}

problem with this approach is that I navigate to the settings page, rotate the device, and it momentarily shows the correct settings page, before flicking back to my main view.

I think there is a threading problem here. But maybe my whole approach is wrong. Can somebody suggest a better solution?

Answer 1

I’m not sure I understand the problem. You want the settings view (loaded from NIB) to autorotate? You should just return YES for the orientation you want the autorotation to be performed in the shouldAutorotateToInterfaceOrientation: and set the autoresizing mask of the views inside the XIB accordingly to your needs.

There’s no need to call back the main view controller and tell him to push a new settings view controller. The rotation behavior of the views is determined by the autoresizing mask properties of each view and the implementation of shouldAutorotateToInterfaceOrientation: method of the associated view controller and just that. If want to do more advanced animations, though, you can set up and manage them in the willRotateToInterfaceOrientation:duration: and didRotateFromInterfaceOrientation: methods.