[iphone] Detecting iOS orientation change instantly

I have a game in which the orientation of the device affects the state of the game. The user must quickly switch between Landscape, Portrait, and Reverse Landscape orientations. So far I've been registering the game for orientation notifications via:

[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];

But it is far too slow - there seems to be about a second delay between rotating the phone and the notification actually being fired. I need a way to INSTANTLY detect changes in the device's orientation. I have tried experimenting with the gyroscope, but am not yet familiar enough with it to know whether or not it is the solution I am looking for.

Why you didn`t use

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

?

Or you can use this

-(void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration

Or this

-(void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation

Hope it owl be useful )

For my case handling UIDeviceOrientationDidChangeNotification was not good solution as it is called more frequent and UIDeviceOrientation is not always equal to UIInterfaceOrientation because of (FaceDown, FaceUp).

I handle it using UIApplicationDidChangeStatusBarOrientationNotification:

//To add the notification
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didChangeOrientation:)

//to remove the
[[NSNotificationCenter defaultCenter]removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];

 ...

- (void)didChangeOrientation:(NSNotification *)notification
{
    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;

    if (UIInterfaceOrientationIsLandscape(orientation)) {
        NSLog(@"Landscape");
    }
    else {
        NSLog(@"Portrait");
    }
}

Try making your changes in:

- (void) viewWillLayoutSubviews {}

The code will run at every orientation change as the subviews get laid out again.

Add a notifier in the viewWillAppear function

-(void)viewWillAppear:(BOOL)animated{
  [super viewWillAppear:animated];
  [[NSNotificationCenter defaultCenter] addObserver:self  selector:@selector(orientationChanged:)    name:UIDeviceOrientationDidChangeNotification  object:nil];
}

The orientation change notifies this function

- (void)orientationChanged:(NSNotification *)notification{
   [self adjustViewsForOrientation:[[UIApplication sharedApplication] statusBarOrientation]];
}

which in-turn calls this function where the moviePlayerController frame is orientation is handled

- (void) adjustViewsForOrientation:(UIInterfaceOrientation) orientation {

    switch (orientation)
    {
        case UIInterfaceOrientationPortrait:
        case UIInterfaceOrientationPortraitUpsideDown:
        { 
        //load the portrait view    
        }

            break;
        case UIInterfaceOrientationLandscapeLeft:
        case UIInterfaceOrientationLandscapeRight:
        {
        //load the landscape view 
        }
            break;
        case UIInterfaceOrientationUnknown:break;
    }
}

in viewDidDisappear remove the notification

-(void)viewDidDisappear:(BOOL)animated{
   [super viewDidDisappear:animated];
   [[NSNotificationCenter defaultCenter]removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}

I guess this is the fastest u can have changed the view as per orientation

@vimal answer did not provide solution for me. It seems the orientation is not the current orientation, but from previous orientation. To fix it, I use [[UIDevice currentDevice] orientation]

- (void)orientationChanged:(NSNotification *)notification{
    [self adjustViewsForOrientation:[[UIDevice currentDevice] orientation]];
}

Then

- (void) adjustViewsForOrientation:(UIDeviceOrientation) orientation { ... }

With this code I get the current orientation position.