iPad orientation change issue

问题:

My iPhone application is displaying some odd behavior when run on the iPad with respect to supporting orientation changes.

The app starts up with a view controller (call it view A for the sake of argument) and navigation controller, and shouldAutorotateToInterfaceOrientation is returning YES for portrait only. Onto the navigation controller, I push a view controller (view B) that also returns YES for portrait only. Then, I push another view controller (view C) onto the nav controller that supports all rotations and adjusts the items on screen based on the orientation to rotate to.

When this is run on the iPhone simulator and device, if you rotate to landscape on view C and then tap the back button to return to view B, it does the right thing and shifts view B back to portrait mode. (In the simulator, it even rotates the simulator back to portrait automagically.)

The problem I am experiencing is that, when I do this exact same sequence of events on the iPad simulator and device, the view B that appears is not rotated back to portrait, and the nav controller still shows the information for view C. Then, I tap on the back button, and the view stays the same but the nav controller shows normal for view B (but all still in landscape mode). Then, if I tap the back button again, view A appears under the view B nav bar items, and finally tapping back again puts me on view A with nav bar A items.

If I go to view B on the iPad and start to rotate around, shouldAutorotateToInterfaceOrientation fires with NO until I reach portrait mode, and then all returns to normal.

The application is being built with the latest released version of the iPhone SDK, and has build settings as follows: Base SDK of iPhone Simulator 4.0, Targeted Device Family of iPhone, iPhone OS Deployment Target of iPhone OS 3.1.3.

Any ideas?

回答1:

Apple states:

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

Response: 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.

http://developer.apple.com/iphone/library/qa/qa2010/qa1688.html

You may be able to set device orientation within the navigation controller instead of within individual views. Then you could check which view is on the stack and rotate based on the result. In this way, the navigation controller handles all orientation as well.

回答2:

Here is some code i'm using to prevent that error:

- (void)viewDidLoad {  
    if (self.interfaceOrientation == UIInterfaceOrientationPortrait) {
        self.view.transform = CGAffineTransformIdentity;
        self.view.transform = CGAffineTransformMakeRotation(M_PI/2);
        self.view.bounds = CGRectMake(0.0, 0.0, 480, 320);
    }
    [UIView commitAnimations];
}

and

- (void)viewDidLoad {
    if (self.interfaceOrientation == UIInterfaceOrientationLandscapeRight) {
        self.view.transform = CGAffineTransformIdentity;
        self.view.transform = CGAffineTransformMakeRotation(-(M_PI / 2));
        self.view.bounds = CGRectMake(0, 0, 320, 480);;
    }
    [UIView commitAnimations];
}

Based on what orientation the device is in, you will need to modify some of the code.