Iphone 重新访问时，UIView很少不旋转的可能原因有哪些？

我将此代码放入所有ViewController中：

    UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];

    if (orientation == UIInterfaceOrientationLandscapeRight) {
        CGAffineTransform transform = self.view.transform;

        // Use the status bar frame to determine the center point of the window's content area.
        //CGRect statusBarFrame = [[UIApplication sharedApplication] statusBarFrame];
        //CGRect bounds = CGRectMake(0, 0, statusBarFrame.size.height, statusBarFrame.origin.x);
        CGPoint center = CGPointMake(320/2, 480/2);

        // Set the center point of the view to the center point of the window's content area.
        self.view.center = center;

        // Rotate the view 90 degrees around its new center point.
        transform = CGAffineTransformRotate(transform, (M_PI / 2.0));
        self.view.transform = transform;
    }   

我还有：

 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations

    return (interfaceOrientation == UIInterfaceOrientationLandscapeRight);
}

---

我可以看到代码正常工作，但偶尔会有一次，主视图控制器在我将其视图放回主视图后，无法为横向模式旋转。发生这种情况的机会非常少，但这让我很烦恼。此外，我可以看到它在iphone上出现的频率更高。在模拟器上，我回忆起它从未发生过。你知道可能的原因是什么吗？提前谢谢。

我找到了我的iphone程序的原因

可能的原因之一是记忆。当系统内存不足时，将调用以下方法：

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

调用此方法时，将卸载不可见的UIView。当您即将再次看到此视图时，设备会重新加载它，但可能是因为您在重新加载时不会调用它的位置设置了旋转等参数。您可以使用：

- (void)viewDidLoad {

    UIApplication* application = [UIApplication sharedApplication];
    application.statusBarOrientation = UIInterfaceOrientationLandscapeRight;

    CGAffineTransform landscapeTransform = CGAffineTransformMakeRotation([MyMath radd:90]);
    landscapeTransform = CGAffineTransformTranslate (landscapeTransform, -80, 83);

    [self.view setTransform: landscapeTransform];
    [super viewDidLoad];
}

它发生在设备中，因为我们谈论的是真实设备上的真实内存。使用模拟器时，可以使用硬件>模拟内存警告