一、基础知识
1、初识3个枚举
1.1、UIDevice.h文件中：设备方向
typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
UIDeviceOrientationUnknown,
UIDeviceOrientationPortrait, // Device oriented vertically, home button on the bottom
UIDeviceOrientationPortraitUpsideDown, // Device oriented vertically, home button on the top
UIDeviceOrientationLandscapeLeft, // Device oriented horizontally, home button on the right
UIDeviceOrientationLandscapeRight, // Device oriented horizontally, home button on the left
UIDeviceOrientationFaceUp, // Device oriented flat, face up
UIDeviceOrientationFaceDown // Device oriented flat, face down
} API_UNAVAILABLE(tvos);
1.2、UIApplication.h文件中：界面方向
typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
UIInterfaceOrientationUnknown = UIDeviceOrientationUnknown,
UIInterfaceOrientationPortrait = UIDeviceOrientationPortrait,
UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,
UIInterfaceOrientationLandscapeLeft = UIDeviceOrientationLandscapeRight,
UIInterfaceOrientationLandscapeRight = UIDeviceOrientationLandscapeLeft
} API_UNAVAILABLE(tvos);
1.3、UIApplication.h文件中：界面方向掩码
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),
} API_UNAVAILABLE(tvos);
2、3个枚举之间的关系
2.1、UIDeviceOrientation和UIInterfaceOrientation有相同意义的枚举
2.2、UIInterfaceOrientationMask是通过UIInterfaceOrientation的不同值取或运算
3、获取横竖屏状态的方法
3.1、获取UIDeviceOrientation
UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation；
3.2、获取UIInterfaceOrientation
UIInterfaceOrientation interfaceOrientation = [UIApplication sharedApplication].statusBarOrientation；
二、原理
1、常见的UI 架构：
image.png
我们是某些界面需要横屏，所以必须要把系统的询问细化到每个控制器的方法才行。
image.png
2、结合上图，我们看下一个横竖屏事件的传递过程：
- 先是捕获到一个横屏事件
- 接下来系统会找到当前用户操作的那个 APP
- APP 会找到当前的窗口 window
- 窗口 window 会找到根控制器，这个时候事件终于传到我们开发者手里了
- 对于我们自定义的根控制器，它需要把这个事件传递到 UITabbarController
- 对于 UITabbarController，需要把事件传递到 UINavigationController
- 对于 UINavigationController，需要把事件传递到我们自己的控制器
- 最后在我们自己的控制器中决定某个界面是否需要横屏
3、现象
3.1.push ViewController的时候：只有才会触发（如果一开始就是横屏是不会去调用shouldAutorotate方法）
3.2.present ViewController的时候：都会去调用shouldAutorotate方法
三、实战应用
1、应用场景
1.1.全应用都是竖屏
image.png
1.2.大部分页面都是竖屏，只有个别页面是可以横竖屏切换（eg.视频播放页面）
// 1.在appDelegate中重写
- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)aWindow {
UIInterfaceOrientationMask mask = [self.viewController.currentTopViewController supportedInterfaceOrientations];
return mask;
}
// 2、在ViewController的基类中实现统一竖屏（只能竖屏的ViewController就继承该基类）
#pragma mark - rotation
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
return UIInterfaceOrientationMaskPortrait;
}
// default value is YES
- (BOOL)shouldAutorotate {
return NO;
}
// default value
// iPhone: UIInterfaceOrientationMaskPortraitUpsideDown
// iPad: UIInterfaceOrientationMaskAll
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
return UIInterfaceOrientationPortrait;
}
- (UIInterfaceOrientation)navigationControllerPreferredInterfaceOrientationForPresentation:(UINavigationController *)navigationController {
return UIInterfaceOrientationPortrait;
}
// 3、在需要能够横竖屏切换的界面重写方法
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
return UIInterfaceOrientationMaskAllButUpsideDown;
}
- (BOOL)shouldAutorotate {
return YES;
}
注意：我们的项目中可能又成千上万个控制器，如果每个控制器都实现是否横竖屏转动的方法显然不大实际。
推荐↓
1.在UIViewController的或者中实现即可（例如：统一不能旋转横竖屏）
2.特殊可以横竖屏切换的页面，在ViewController重写方法（例如：视频播放页面能旋转横竖屏）
1.3.大部分都是可以横竖屏切换，只有少部分页面固定（跟1.2相反）
2、手动横竖屏方法（亲测能过包）
// 手动横屏
[[UIDevice currentDevice] setValue:@(UIInterfaceOrientationLandscapeRight) forKey:@"orientation"];
[UIViewController attemptRotationToDeviceOrientation];
// 手动竖屏
[[UIDevice currentDevice] setValue:@(UIInterfaceOrientationPortrait) forKey:@"orientation"];
[UIViewController attemptRotationToDeviceOrientation];
// call this method when your return value from shouldAutorotateToInterfaceOrientation: changes
// if the current interface orientation does not match the current device orientation, a rotation may occur provided all relevant view controllers now return YES from shouldAutorotateToInterfaceOrientation:
+ (void)attemptRotationToDeviceOrientation API_AVAILABLE(ios(5.0)) API_UNAVAILABLE(tvos);