旋转相关的配置方法

//UIViewController.m
#pragma mark - rotation
//定义是否支持旋转
-(BOOL)shouldAutorotate
{
    return YES;
}
//定义支持旋转的方向
-(UIInterfaceOrientationMask)supportedInterfaceOrientations
{
    return isPad ? UIInterfaceOrientationMaskLandscape : UIInterfaceOrientationMaskPortrait;
}
//定义第一次进来的时候的方向
-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
    return isPad ? UIInterfaceOrientationLandscapeLeft : UIInterfaceOrientationPortrait;
}

旋转相关的生命周期方法

//UIViewController.m
//1

//被调用。这个方法是发生在翻转开始之前。一般用来禁用某些控件或者停止某些正在进行的活动，比如停止视频播放。

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{

NSLog(@"willRotateToInterfaceOrientation %d",toInterfaceOrientation);

}

//2
//window调整显示的view controller的bounds，由于view controller的bounds发生变化，将会触发 **viewWillLayoutSubviews** 方法。这个时候
self.**interfaceOrientation**和**statusBarOrientation**方向还是原来的方向。

//3

//这个方法发生在翻转的过程中，一般用来定制翻转后各个控件的位置、大小等。可以用另外两个方法来代替：

- (void) willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation)) {
        //如果当前是竖屏要完成的事情
    }else {
        //其他情况完成事情
    }
}

//4

//这个方法发生在整个翻转完成之后。一般用来重新启用某些控件或者继续翻转之前被暂停的活动，比如继续视频播放

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation{

NSLog(@"didRotateFromInterfaceOrientation %d",fromInterfaceOrientation);

}

但是上面三个方法(1, 2, 4)在iOS8之后已经是Deprecated状态了

// This method is called when the view controller's view's size is changed by its parent (i.e. for the root view controller when its window rotates or is resized). 
// If you override this method, you should either call super to propagate the change to children or manually forward the change to children.
- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id <UIViewControllerTransitionCoordinator>)coordinator NS_AVAILABLE_IOS(8_0);

// This method is called when the view controller's trait collection is changed by its parent.
// If you override this method, you should either call super to propagate the change to children or manually forward the change to children.
- (void)willTransitionToTraitCollection:(UITraitCollection *)newCollection withTransitionCoordinator:(id <UIViewControllerTransitionCoordinator>)coordinator NS_AVAILABLE_IOS(8_0);

UIDeviceOrientation & UIInterfaceOrientation

UIDeviceOrientation
机器硬件方向，只读//可以反射设置
    [[UIDevice currentDevice] valueForKey:@"orientation"]
UIInterfaceOrientation
程序界面方向，读写。
    [[UIApplication sharedApplication] statusBarOrientation]

appDelegate的application:supportedInterfaceOrientationsForWindow:

当前controller能否旋转，取决于下面这个代理方法的返回值和controller的设置，这个值默认是plist里面UIInterfaceOrientation决定的，一般不需要重写这个方法。

-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window

注意iOS7

//iOS 7：
//    竖屏：  
    UIScreen.mainScreen().bounds: (0.0,0.0,320.0,568.0)  
//    横屏：  
    UIScreen.mainScreen().bounds: (0.0,0.0,320.0,568.0)  
//iOS 8：
//    竖屏：  
    UIScreen.mainScreen().bounds: (0.0,0.0,320.0,568.0)  
//    横屏：  
    UIScreen.mainScreen().bounds: (0.0,0.0,568.0,320.0) 

还要注意弹框View与旋屏

参考文献

iOS屏幕旋转各类集锦(一) 设置
iOS屏幕旋转各类集锦(二) 生命周期
详解iOS开发中处理屏幕旋转的几种方法 （注意设备旋转和屏幕旋转的不同）