Determine UIInterfaceOrientation on iPad

问题:

I don't need to specify the orientation in this case, I just need to detect it, but I'm having trouble. I have conditional code that should only work in portrait, and if the device is in landscape I need to do something else. Since the deviceOrientation is not necessarily the same as the interfaceOrientation, I can't come up with a way to test for portrait mode.

Most tutorials I find on Google are ways to force landscape or do some sort of rotation. The only thing I want to do is just determine what the orientation is. Here is my code, which is not working:

-(void)viewDidLoad {
    [super viewDidLoad];
    //currentOrientation is declared as UIInterfaceOrientation currentOrientation
    currentOrientation = [[UIApplication sharedApplication] statusBarOrientation];
NSLog(@"%@",currentOrientation);  // == NULL
}

I need to determine the value of the interfaceOrientation and program conditionally. Thanks for your help!

回答1:

Are you aware of the interfaceOrientation property of the UIViewController class?

- (void) viewDidLoad {
    [super viewDidLoad];
    BOOL isPortrait = UIDeviceOrientationIsPortrait(self.interfaceOrientation);
    // now do whatever you need
}

Or are you after [[UIDevice currentDevice] orientation]?

回答2:

Especially at launch I have found the following to be always accurate for the UI, regardless of what the UIDevice says the orientation is.

[UIApplication sharedApplication].statusBarOrientation

回答3:

self.interfaceOrientation is unreliable in certain situations. For example, re-arranging tabs in a tabbar application returns incorrect value.

However [UIApplication sharedApplication].statusBarOrientation is always reliable. You saved me a lot of time slycrel. Thank you.

回答4:

UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;

if ((orientation == UIInterfaceOrientationLandscapeLeft)
||  (orientation == UIInterfaceOrientationLandscapeRight) )
{
    //Landscape
}
else
{
    //Portrait
}

回答5:

I know it is a very old post. How ever I would like to add a point to say it is better to check status bar orientation is better. When ever you call self.interfaceorientation it is calling shouldRotateToOrientation every time. If you have written some code in that method it will be executed. So be cautious!.

回答6:

    UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
    UIInterfaceOrientation statusBarOrientation = [UIApplication sharedApplication].statusBarOrientation; 

    if(deviceOrientation == UIDeviceOrientationFaceUp || deviceOrientation == UIDeviceOrientationFaceDown){
        if(debug){
            NSLog(@"Nothing to change because it is gone to Flat");
        }
        return;
    }
    if(deviceOrientation !=statusBarOrientation){
        if(debug){
            NSLog(@"\nApple has a bug?:\n UIDeviceOrientation : %d, UIInterfaceOrientation: %d",deviceOrientation, statusBarOrientation  );
        }
    }

You won't believe me until you will see at the console the second output! Some situations - and they exists! - is displayed the last NSLog content!

Than you have to do some workarounds to go on that way, where iOS has no bug, good luck for everyone!

Ah that ... forum moderator maybe will delete this post too, because this doesn't meant to be and answer in his opinion!

I hope it helps for somebody once, it happens on iphone too...(there I got)

回答7:

Mix it up a little:

BOOL isLandscape = self.view.frame.size.width > self.view.frame.size.height;

(edit) Obviously the previous answers are the correct way to do this and this solution would fail in a situation where view controllers are not full-screen.

回答8:

-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{</br>
   if (UIDeviceOrientationIsLandscape(toInterfaceOrientation)) {</br>
        some instructions;
   } else { 
        some instructions;
   }
}

This is a snippet from one of my programs. You could of course use the if statement in your ViewDidLoad notification as well.

回答9:

I already voted up the answer by @slycrel, but I would like to take the time to write this, and point some things out that seems to be lost in this old question, and lots of other questions on the subject.

It's true that Apple does not really want us to update most of our UI based on orientation changes, but it is still totally possible and sometimes necessary on a case by case scenario, and it will be that way until Apple improves their new(ish) APIs (e.g. viewWillTransitionToFrame: would be way more useful than viewWillTransitionToSize:. Just sayin')

Why I voted up the answer by @slycrel is related to what you need to keep in mind as the logical difference between UIDeviceOrientation and UIInterfaceOrientation.

Tthe status bar is what denotes an application's currently known UIInterfaceOrientation. All this stuff about FaceUp, FaceDown is only related to a device's orientation, not necessarily your application's. An application does not support device orientations anyway. Really, UIDeviceOrientation can be ignored completely if all you have to do is make sure you layout and animate things appropriately in your interface, which is 99% of an application developer's use cases. This is currently achieved with the status bar's UIInterfaceOrientation from @slycrel's answer:

[UIApplication sharedApplication].statusBarOrientation

It should be noted, the readwrite version of this property is deprecated, the readonly version is not.

Take this example:

• I have an application that supports ALL interfaces orientations, and a root view controller that supports them as well.
• Now, I am presenting a UIViewController that will result in the status bar orientation to become landscape.
• Which landscape orientation (left or right) it goes to is based on what is returned by preferredInterfaceOrientationForPresentation for that view controller, what the current device orientation is, and what interface orientations the view controller supports (see next point).
• The status bar will go to landscape, regardless of what the current device orientation is, because this view controller only supports landscape based on what is returned by supportedInterfaceOrientations. Lets say we support both landscape left and right with UIInterfaceOrientationMaskLandscape.
• I also want to conditionally animate this view controller into position with a rotation transform. This will only be necessary when going from portrait or portrait upside down, to landscape left or landscape right. Otherwise it will be a more simple presentation animation without rotation.
• Then, after some time and device use, I dismiss that view controller.
• Now I want to conditionally animate this view controller off the screen with another rotation transform. This will only be necessary when going from landscape left or landscape right, to portrait or portrait upside down. Otherwise it will be a more simple dismissal animation without rotation.
• At this point, the status bar's orientation will become whatever the system decides is appropriate for the combination of your root view controller's preferred interface orientation and supported interface orientations, as well as the device's current UIDeviceOrientation.
• Since the view controller we are going to supports ALL interface orientations, if your device's orientation is FaceUp or FaceDown, you can not reliably guess the next UIInterfaceOrientation based on UIDeviceOrientation, and you do not have to anyway.
• So... status bar orientation to the rescue!

The previous example is possible, because the status bar orientation is not updated when a view controller transition is about to start (the system asks a transition delegate for an animator, etc.). Then it is updated when the transition starts animating (e.g. by the time animationTransition: is called). This way you should have a good comparison just using the initial and current values of the status bar's UIInterfaceOrientation.

Even without using view controller transitions, it should still be safe to update views based on the status bar orientation.

Keep in mind, if you are manually updating the status bar, and if you are not using "View controller-based status bar appearance" in your Info.plist, then your application's logic must be aware when the status bar will and did change orientation. You will probably be looking for a couple NSNotification names for these cases, which are:

• UIApplicationWillChangeStatusBarOrientationNotification
• UIApplicationDidChangeStatusBarOrientationNotification

As well as these UIApplicationDelegate methods:

- (void)application:(UIApplication *)application willChangeStatusBarOrientation:(UIInterfaceOrientation)newStatusBarOrientation duration:(NSTimeInterval)duration;
- (void)application:(UIApplication *)application didChangeStatusBarOrientation:(UIInterfaceOrientation)oldStatusBarOrientation;
- (UIInterfaceOrientationMask)supportedInterfaceOrientationsForWindow:(nullable UIWindow *)window

And this other helpful UIApplication property:

@property(nonatomic,readonly) NSTimeInterval statusBarOrientationAnimationDuration;

回答10:

As of iOS8, APIs have been deprecated or return unhelpful results such as .FaceUp .FaceDown

This is because Apple does NOT want you to update your UI using orientation, but rather by using size classes, constraints, and proportion (using n% of superview).

Indeed, orientation dependent code might fail to provide good results across the whole range of device and use case (especially multitasking)