AutoRotatingWindow.m

@implementation AutoRotatingWindow

- (instancetype)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self)
  {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willRotate:) name:UIApplicationWillChangeStatusBarOrientationNotification object:nil];
  }
  return self;
}
- (void)dealloc
{
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)willRotate:(NSNotification *)n
{
  UIInterfaceOrientation o = [n.userInfo[UIApplicationStatusBarOrientationUserInfoKey] intValue];
  CGSize s = [UIScreen mainScreen].bounds.size;
  UIInterfaceOrientation co = [UIApplication sharedApplication].statusBarOrientation;
  CGFloat w = s.width;
  CGFloat h = s.height;
  if (co == UIInterfaceOrientationLandscapeLeft || co == UIInterfaceOrientationLandscapeRight)
  {
    w = s.height;
    h = s.width;
  }
  
  switch (o) {
    case UIInterfaceOrientationPortrait:
      self.bounds = CGRectMake(0, 0, w, h);
      self.transform = CGAffineTransformIdentity;
      break;
    case UIInterfaceOrientationLandscapeLeft:
      self.bounds = CGRectMake(0, 0, h, w);
      self.transform = CGAffineTransformMakeRotation(M_PI * 270.f/180.f);
      break;
    case UIInterfaceOrientationLandscapeRight:
      self.bounds = CGRectMake(0, 0, h, w);
      self.transform = CGAffineTransformMakeRotation(M_PI * 90.f/180.f);
      break;
    case UIInterfaceOrientationPortraitUpsideDown:
      self.bounds = CGRectMake(0, 0, w, h);
      self.transform = CGAffineTransformMakeRotation(M_PI * 360.f/180.f);
      break;
    default:
      break;
  }
}
@end