iOS屏幕旋转（横竖屏）

一、屏幕旋转方向监听

1、UIDeviceOrientation：设备方向

iOS 定义了七种设备方向：

typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
    UIDeviceOrientationUnknown,                 // 未知方向，可能是设备(屏幕)斜置
    UIDeviceOrientationPortrait,                // 设备(屏幕)直立
    UIDeviceOrientationPortraitUpsideDown,      // 设备(屏幕)直立，上下顛倒
    UIDeviceOrientationLandscapeLeft,           // 设备(屏幕)向左横置
    UIDeviceOrientationLandscapeRight,          // 设备(屏幕)向右橫置
    UIDeviceOrientationFaceUp,                  // 设备(屏幕)朝上平躺
    UIDeviceOrientationFaceDown                 // 设备(屏幕)朝下平躺
};
//注意：UIDeviceOrientation参考home键方向，如：home方向在右，设备(屏幕)方向向左（UIDeviceOrientationLandscapeLeft）

当设备方向变化时候，发出UIDeviceOrientationDidChangeNotification通知；注册监听该通知，可以针不同的设备方向处理视图展示。
注：手机锁定竖屏后，UIDeviceOrientationDidChangeNotification通知就失效了。
代码如下：

//开启和监听 设备旋转的通知（不开启的话，设备方向一直是UIInterfaceOrientationUnknown）
if (![UIDevice currentDevice].generatesDeviceOrientationNotifications) {
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
}
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(handleDeviceOrientationChange:) 
                                     name:UIDeviceOrientationDidChangeNotification object:nil];
//设备方向改变的处理
- (void)handleDeviceOrientationChange:(NSNotification *)notification{
    UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
    switch (ddeviceOrientation) {
        case UIDeviceOrientationFaceUp:
            NSLog(@"屏幕朝上平躺");
            break;
        case UIDeviceOrientationFaceDown:
            NSLog(@"屏幕朝下平躺");
            break;
        case UIDeviceOrientationUnknown:
            NSLog(@"未知方向");
            break;
        case UIDeviceOrientationLandscapeLeft:
            NSLog(@"屏幕向左横置");
            break;
        case UIDeviceOrientationLandscapeRight:
            NSLog(@"屏幕向右橫置");
            break;
        case UIDeviceOrientationPortrait:
            NSLog(@"屏幕直立");
            break;
        case UIDeviceOrientationPortraitUpsideDown:
            NSLog(@"屏幕直立，上下顛倒");
            break;
        default:
            NSLog(@"无法辨识");
            break;
    }
}

//最后在dealloc中移除通知 和结束设备旋转的通知
- (void)dealloc{
    //...
    [[NSNotificationCenter defaultCenter]removeObserver:self];
    [[UIDevice currentDevice]endGeneratingDeviceOrientationNotifications];
}

2、UIInterfaceOrientation：界面方向

iOS 定义了五种界面方向

typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
    UIInterfaceOrientationUnknown            = UIDeviceOrientationUnknown,       //未知方向
    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,               //界面直立
    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,  //界面直立，上下颠倒
    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,   //界面朝左
    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft    //界面朝右
} __TVOS_PROHIBITED;

注：界面方向和设别方向有对应关系，如界面的竖直方向就是 设备的竖直方向：UIInterfaceOrientationUnknown = UIDeviceOrientationUnknown

要想界面旋转，
在如图所示选择支持的界面旋转方向：

3321499760416_.pic_hd.jpg

同时在 UIViewController中加入以下两个方法：

///是否支持自动转屏
-(BOOL)shouldAutorotate
{
    return YES;///很明显如果返回YES就可以，返回NO就不行
}
///如果上面方法返回YES则会根据这个方法判断支持的方向
-(UIInterfaceOrientationMask)supportedInterfaceOrientations
{
    return UIInterfaceOrientationMaskAll;///这个是所有方向
}

当界面方向变化时候，先后发出 UIApplicationWillChangeStatusBarOrientationNotification和 UIApplicationDidChangeStatusBarOrientationNotification通知，手机锁定竖屏后，这两个通知也失效了；注册监听这两个通知，可以针对不同的界面方向处理视图展示。
代码如下所示：

//以监听UIApplicationDidChangeStatusBarOrientationNotification通知为例
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(handleStatusBarOrientationChange:) 
                                     name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
//界面方向改变的处理
- (void)handleStatusBarOrientationChange: (NSNotification *)notification{
    UIInterfaceOrientation interfaceOrientation = [[UIApplication sharedApplication] statusBarOrientation];
    switch (interfaceOrientation) {
        case UIInterfaceOrientationUnknown:
            NSLog(@"未知方向");
            break;
        case UIInterfaceOrientationPortrait:
            NSLog(@"界面直立");
            break;
        case UIInterfaceOrientationPortraitUpsideDown:
            NSLog(@"界面直立，上下颠倒");
            break;
        case UIInterfaceOrientationLandscapeLeft:
            NSLog(@"界面朝左");
            break;
        case UIInterfaceOrientationLandscapeRight:
            NSLog(@"界面朝右");
            break;
        default:
            break;
    }
}
//最后在dealloc中移除通知
- (void)dealloc{
    //...
    [[NSNotificationCenter defaultCenter]removeObserver:self];
    [[UIDevice currentDevice]endGeneratingDeviceOrientationNotifications];
}

3、UIInterfaceOrientationMask
UIInterfaceOrientationMask是为了集成多种UIInterfaceOrientation而定义的类型，和UIViewController相关，一共有7种

iOS中的UIInterfaceOrientationMask定义

typedef NS_OPTIONS(NSUInteger, UIInterfaceOrientationMask) {
    UIInterfaceOrientationMaskPortrait = (1 << UIInterfaceOrientationPortrait),
    UIInterfaceOrientationMaskLandscapeLeft = (1 << UIInterfaceOrientationLandscapeLeft),
    UIInterfaceOrientationMaskLandscapeRight = (1 << UIInterfaceOrientationLandscapeRight),
    UIInterfaceOrientationMaskPortraitUpsideDown = (1 << UIInterfaceOrientationPortraitUpsideDown),
    UIInterfaceOrientationMaskLandscape = (UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
    UIInterfaceOrientationMaskAll = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight | UIInterfaceOrientationMaskPortraitUpsideDown),
    UIInterfaceOrientationMaskAllButUpsideDown = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
} __TVOS_PROHIBITED;

在ViewController可以重写- (UIInterfaceOrientationMask)supportedInterfaceOrientations方法返回类型，来决定UIViewController可以支持哪些界面方向。

//支持界面直立
- (UIInterfaceOrientationMask)supportedInterfaceOrientations{
    return UIInterfaceOrientationMaskPortrait;
}

二、视图控制器中旋转方向的设置

1、禁止横屏操作

• 方法一：在项目的General-->Deployment Info-->Device Orientation中，只勾选Portrait(竖屏)
• 方法二：Device Orientation默认设置，在Appdelegate中实现supportedInterfaceOrientationsForWindow:只返回UIInterfaceOrientationMaskPortraitt(竖屏)

-  (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window  {  
     return UIInterfaceOrientationMaskPortrait;  
}

参考链接：http://www.cocoachina.com/ios/20170711/19808.html

项目Demo托管在[GitHub][]上
[GitHub]:https://github.com/lizishiye/DeviceOrientation_Demo