Why won't my UIViewController rotate with the device?

Q:  Why won't my UIViewController rotate with the device?

A: The UIViewController class provides the fundamental view-management model for iOS applications. It provides automatic support for rotating the views of the view controller in response to changes to the orientation of the device. If the autoresizing properties of your view and subviews are properly configured, this behavior is automatic in most cases. Here is a fairly exhaustive list of reasons a view controller may not rotate.

• You have added your view controller's UIView property to UIWindow as a subview.

  Developers are discouraged from adding the view property of any view controller as a subview of UIWindow. Your application's root view controller should be assigned to the app window's rootViewController property either in Interface Builder, or at runtime before returning from application:didFinishLaunchingWithOptions:. If you need to display content from more than one view controller simultaneously, you should define your own container view controller and use it as the root view controller. See Creating Custom Container View Controllers.

  Beginning with iOS 6, if a root view controller has not been assigned to the app's window, supported orientations are determined only by the UIApplication object. Further, view controllers will not be notified of orientation changes, which may result in unexpected behavior.

• The view controller does not support the new orientation.

  Beginning with iOS 6, a view controller can limit its supported orientations by overriding this method:

  - (NSUInteger)supportedInterfaceOrientations

  The default implementation of supportedInterfaceOrientations returns a rotation mask of the recommended orientation values for the current device's idiom. That is, UIInterfaceOrientationMaskAll is returned on iPad devices and UIInterfaceOrientationMaskAllButUpsideDown is returned on iPhone devices. There is little need to override this method unless the content managed by the view controller must only be displayed in a subset of these orientations. If you override this method, your implementation must return a bitwise combination of UIInterfaceOrientationMask values.

  On iOS 5 and below, a view controller can support multiple orientations by overriding this method:

  - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

  Even if shouldAutorotateToInterfaceOrientation is implemented, you should make sure it returns YES for all the orientations you wish to support. The default implementation returns YES if interfaceOrientation is equal to UIInterfaceOrientationPortrait, locking the view controller into portrait orientation. To support all orientations, simply always return YES.

• The application does not support the same orientations as the view controller.

  Beginning with iOS 6, UIKit uses both the UIApplication object and the topmost view controller to determine the supported orientations. The UISupportedInterfaceOrientations key in the app's Info.plist must contain a value for each orientation your app supports. The system uses these values to derive the app's supported orientation mask. The application delegate may implement application:supportedInterfaceOrientationsForWindow: to return a UIInterfaceOrientationMask that is used in place of the values from the app's Info.plist.

  On iOS 5 and below, the values for the UISupportedInterfaceOrientations key in the app's Info.plist only serve as a hint to Springboard that it should reposition the status bar before starting your app. They do not restrict the supported orientations of your app after it has been launched.

• The view controller declined to rotate.

  Beginning with iOS 6, when UIKit determines that rotation may need to occur, it calls the shouldAutorotate method of the topmost view controller to determine whether to proceed with the rotation. The default implementation of this method returns YES; however, a view controller may dynamically disable automatic rotation at runtime by overriding shouldAutorotate to return NO.

• The view controller is a child of another view controller.

  Beginning with iOS 6, only the topmost view controller (alongside the UIApplication object) participates in deciding whether to rotate in response to a change of the device's orientation. More often than not, the view controller displaying your content is a child of UINavigationController, UITabBarController, or a custom container view controller. You may find yourself needing to subclass a container view controller in order to modify the values returned by its supportedInterfaceOrientations and shouldAutorotate methods.

• The view controller overrides init or initWithNibName:bundle: but does not invoke the superclass' implementation. For the object to be initialized properly, you must call super on any init or initWithNibName method you are overriding in your view controllers.

• All child view controllers in your UITabBarController or UINavigationController do not agree on a common orientation set.

  On iOS 5 and below, to make sure that all your child view controllers rotate correctly, you must implement shouldAutorotateToInterfaceOrientation for each view controller representing each tab or navigation level. Each must agree on the same orientation for that rotate to occur. That is, they all should return YES for the same orientation positions.

• The view controller is altering the layout of its subviews programmatically.

  Certain layouts are impossible to realize using autoresizing masks alone. A view controller can manually layout its subviews by altering their frame, bounds, or center properties. Developers should not place layout code in any of the rotation methods overridden by the view controller (e.g. shouldAutorotateToInterfaceOrientation). There are cases where the interface may rotate without these methods being called, leaving the view controller's subviews in an inconsistent state.

  If the app only supports iOS 5 or later, you should place layout code in the view controller's viewWillLayoutSubviews: or viewDidLayoutSubviews: methods.

  If the app must support iOS 4, you should place layout code in the layoutSubviews method of the view controller's view.

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