方向：Xcode 4.2中的纵向和横向

Question

I wanted to make my project support full orientation. I'm on xcode 4.2 My implementation gives me one warning:

that's the code :

#import "OrientationTutorialViewController.h"

@implementation OrientationTutorialViewController

@synthesize portraitView, landscapeView;


- (void)viewDidLoad 
{
    [super viewDidLoad];

    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:@"UIDeviceOrientationDidChangeNotification" object:nil];

}

- (void) orientationChanged:(id)object
{  
    UIInterfaceOrientation interfaceOrientation = [[object object] orientation];

    if (interfaceOrientation == UIInterfaceOrientationPortrait || interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown) 
    {
        self.view = self.portraitView;
    } 
    else 
    {
        self.view = self.landscapeView;
    }
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation 
{
    return YES;
}



- (void)dealloc 
{
    [super dealloc];
}

@end

Is there a way to fix this warning?

Answer 1

I'm guessing you copied this code from this tutorial . This shows the danger of just copying and pasting code from some random person on the Internet.

There are a few problems with this code. First, there's the issue you describe here, where the UIDeviceOrientationDidChangeNotification notification passes back a UIDevice, whose -orientation method returns a UIDeviceOrientation enum. For some reason, the author of this code is assigning that value to a UIInterfaceOrientation enum, instead of dealing with it as a UIDeviceOrientation value. This could be fixed by using the appropriate enum type and comparing against those values.

Second, why are they using a notification for orientation changes, when they just as easily could be using the UIViewController delegate method -didRotateFromInterfaceOrientation: ? That does pass in a UIInterfaceOrientation enum. I recommend replacing the notification and the responder method above with -didRotateFromInterfaceOrientation: . See Apple's many examples of view controller autorotation, as well as their copious documentation, for how to do this.

Third, if they're going to have a method respond to a notification, like in -orientationChanged: above, it should take an NSNotification object, not just a generic id.

Answer 2

I have tried so many of these alternatives, then I found out that you also have to be sure to change the variabel Initial interface orientation to what you want in addition to adding

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation{

return (self.interfaceOrientation == UIInterfaceOrientationLandscapeRight);  
}

somewhere in your implementation file. Just the snippet worked in the beginning, but when adding more views and controllers, it all got messed up until I changed the .plist.

Answer 3

check out this post , it explains it well.

also, you can cast your orientations if needed.

deviceOrientation = (UIDeviceOrientation)[UIApplication sharedApplication].statusBarOrientation;