Detecting iOS orientation change instantly
IphoneObjective CIosOrientationGyroscopeIphone Problem Overview
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.
Iphone Solutions
Solution 1 - Iphone
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
Solution 2 - Iphone
That delay you're talking about is actually a filter to prevent false (unwanted) orientation change notifications.
For instant recognition of device orientation change you're just gonna have to monitor the accelerometer yourself.
Accelerometer measures acceleration (gravity included) in all 3 axes so you shouldn't have any problems in figuring out the actual orientation.
Some code to start working with accelerometer can be found here:
How to make an iPhone App – Part 5: The Accelerometer
And this nice blog covers the math part:
Solution 3 - Iphone
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 )
Solution 4 - Iphone
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");
}
}
Solution 5 - Iphone
Try making your changes in:
- (void) viewWillLayoutSubviews {}
The code will run at every orientation change as the subviews get laid out again.
Solution 6 - Iphone
@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.