TBSplitViewController.h

//
//  TBSplitViewController.h
//
//  Created by Tyler Bunnell on 8/4/12
//  Released under the have fun with this and make cool stuff license.
//

#import <UIKit/UIKit.h>

@interface TBSplitViewController : UISplitViewController
{
  id willRotateObserver;
  id didRotateObserver;
}

@end

TBSplitViewController.m

//
//  TBSplitViewController.m
//
//  Created by Tyler Bunnell on 8/4/12
//  Released under the have fun with this and make cool stuff license.
//
//  This class makes a UISplitViewController respond to orientation changes
//   properly when it is not in focus. For example, when it is contained in
//   a UITabBarController and its tab is not selected.
//
//  This code uses ARC and was written for iOS 6+, though it may
//   work for previous versions.
//  This code uses valueForKey to access private member variables
//   in Apple frameworks. This may cause your application to be rejected,
//   but it is unlikely, as these objects are not being manipulated directly.
//  Thanks to https://github.com/grgcombs/IntelligentSplitViewController/ for
//   information used in this code.
//

#import "TBSplitViewController.h"

@interface TBSplitViewController ()
- (void)addObservers;
- (void)removeObservers;
- (void)sendSplitViewControllerMessagesForOrientation:(UIInterfaceOrientation)orientation;
@end

@implementation TBSplitViewController

// When the view appears, remove our observers to prevent sending the
//  rotation and delegate methods twice
- (void)viewWillAppear:(BOOL)animated
{
  [self removeObservers];
  [super viewWillAppear:animated];
}

// When the view disappears, add our observers so we can be notified of the
//  rotation changes in the background
- (void)viewWillDisappear:(BOOL)animated
{
  [self addObservers];
  [super viewWillDisappear:animated];
}

// In the observers below, we send the messages asynchronously and on the main thread.
//  If we don't, there are problems with the master view not being visible once we
//  switch back to the split view after having rotated in the background.
- (void)addObservers
{
  willRotateObserver =
  [[NSNotificationCenter defaultCenter]
   addObserverForName:UIApplicationWillChangeStatusBarOrientationNotification
   object:nil
   queue:nil
   usingBlock:^(NSNotification *notification) {
     
     UIInterfaceOrientation toOrientation = [[[notification userInfo] valueForKey:UIApplicationStatusBarOrientationUserInfoKey] integerValue];
     NSTimeInterval duration = [[UIApplication sharedApplication] statusBarOrientationAnimationDuration];
     
     dispatch_async(dispatch_get_main_queue(), ^{
       [self willRotateToInterfaceOrientation:toOrientation duration:duration];
       [self sendSplitViewControllerMessagesForOrientation:toOrientation];
     });
     
   }];
  
  didRotateObserver =
  [[NSNotificationCenter defaultCenter]
   addObserverForName:UIApplicationWillChangeStatusBarOrientationNotification
   object:nil
   queue:nil
   usingBlock:^(NSNotification *notification) {
     
     UIInterfaceOrientation fromOrientation = [[[notification userInfo] valueForKey:UIApplicationStatusBarOrientationUserInfoKey] integerValue];
     
     dispatch_async(dispatch_get_main_queue(),^{
       [self didRotateFromInterfaceOrientation:fromOrientation];
     });
     
   }];
}

- (void)removeObservers
{
  [[NSNotificationCenter defaultCenter] removeObserver:willRotateObserver];
  willRotateObserver = nil;
  [[NSNotificationCenter defaultCenter] removeObserver:didRotateObserver];
  didRotateObserver = nil;
}

- (BOOL)shouldAutorotate
{
  return YES;
}

- (void)sendSplitViewControllerMessagesForOrientation:(UIInterfaceOrientation)orientation;
{
  id delegate = [self delegate];
  UIViewController* masterViewController = [[self viewControllers] objectAtIndex:0];
  UIBarButtonItem* barButtonItem = [super valueForKey:@"_barButtonItem"];
  
  // Here, we send the delegate messages as are appropriate for what is happening.
  if(UIInterfaceOrientationIsPortrait(orientation))
  {
    if([delegate respondsToSelector:@selector(splitViewController:willHideViewController:withBarButtonItem:forPopoverController:)])
    {
      UIPopoverController* popoverController = [super valueForKey:@"_hiddenPopoverController"];
      [delegate splitViewController:self willHideViewController:masterViewController withBarButtonItem:barButtonItem forPopoverController:popoverController];
    }
  }
  else if(UIInterfaceOrientationIsLandscape(orientation))
  {
    if([delegate respondsToSelector:@selector(splitViewController:willShowViewController:invalidatingBarButtonItem:)])
    {
      [delegate splitViewController:self willShowViewController:masterViewController invalidatingBarButtonItem:barButtonItem];
    }
  }
  else
  {
    [NSException raise:@"TBUnknownOrientationException" format:@"TBSplitViewController is attempting to rotate to an unknown orientation."];
  }
}

@end