iOS横竖屏切换

导航控制器PUSH

需求：当前竖屏下情况下，导航栏直接PUSH出一个横屏的控制器，并在POP后返回竖屏状态。
效果图：

push.gif

主要实现是通过下面这两步：
①. 让AppDelegate在屏幕方向相关的代理方法中，返回我们期望的屏幕方向

// AppDelegate.h中
typedef NS_ENUM(NSUInteger, ScreenOrientation) {
    PortraitMode = 0,
    LandscapeMode,
    AllButUpsideDownMode,
};

@property (nonatomic, assign) ScreenOrientation viewRotateMode;

// AppDelegate.m中
-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    
    if (self.viewRotateMode == 0) {
        return UIInterfaceOrientationMaskPortrait;
    } else if (self.viewRotateMode == 1) {
        return UIInterfaceOrientationMaskLandscape;
    }
    return UIInterfaceOrientationMaskAllButUpsideDown;
}

- (NSUInteger)supportedInterfaceOrientations
{
    if (self.viewRotateMode == 0) {
        return UIInterfaceOrientationMaskPortrait;
    } else if (self.viewRotateMode == 1) {
        return UIInterfaceOrientationMaskLandscape;
    }
    return UIInterfaceOrientationMaskAllButUpsideDown;
}

②. 通过KVC改变UIDevice的orientation属性

NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationLandscapeLeft];
[[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];

具体实现：
在被push的ViewController中：

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    AppDelegate *delegate =(AppDelegate *) [UIApplication sharedApplication].delegate;
    delegate.viewRotateMode = LandscapeMode;
    NSNumber *orientationUnknown = [NSNumber numberWithInt:UIInterfaceOrientationUnknown];
    [[UIDevice currentDevice] setValue:orientationUnknown forKey:@"orientation"];
    
    NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationLandscapeLeft];
    [[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    AppDelegate *delegate =(AppDelegate *) [UIApplication sharedApplication].delegate;
    delegate.viewRotateMode = PortraitMode;
    NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationPortrait];
    [[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];
}

模态，单个控制器交互后横竖屏切换

一、重载根控制器

@property(nonatomic, readonly) UIInterfaceOrientationMask supportedInterfaceOrientations
在这个属性的文档中有如下解释：
When the user changes the device orientation, the system calls this method on the root view controller or the topmost presented view controller that fills the window. 

iOS 6之后，控制器的方向由根控制器管理，可使用继承或者分类的方式，重载根控制器关于旋转屏幕的三个方法，将方向的选择权归还给子控制器。

@implementation UINavigationController (manualRotate)

- (BOOL)shouldAutorotate {
    return self.topViewController.shouldAutorotate;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return self.topViewController.supportedInterfaceOrientations;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return self.topViewController.preferredInterfaceOrientationForPresentation;
}

@end


@implementation UITabBarController (manualRotate)
//在`iOS 5`及更早的版本中默认返回`NO`, 其他默认返回`YES`
- (BOOL)shouldAutorotate {
    return self.selectedViewController.shouldAutorotate;
}

// shouldAutorotate为Yes时才会被调用
// iPad默认返回UIInterfaceOrientationMaskAll
// iPhone默认返回UIInterfaceOrientationMaskAllButUpsideDown
// 此方法的返回值与AppDelegate的application:supportedInterfaceOrientationsForWindow:的交集才是有效值
// AppDelegate的application:supportedInterfaceOrientationsForWindow:会覆盖工程配置中(Info.plist)的Supported interface orientations
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return self.selectedViewController.supportedInterfaceOrientations;
}

// 系统会默认按statusBar的方向来展示一个新的控制器，即默认按当前方向
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return self.selectedViewController.preferredInterfaceOrientationForPresentation;
}

@end

至此，新的控制器，只需要重载上面的方法就能管理自己的方向了。

二、强制修改设备方向

@implementation UIDevice (manualRotate)
+ (void)setOrientation:(UIInterfaceOrientation)orientation {
    SEL selector = NSSelectorFromString(@"setOrientation:");
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self instanceMethodSignatureForSelector:selector]];
    [invocation setSelector:selector];
    [invocation setTarget:[self currentDevice]];
    NSInteger val = orientation;
    [invocation setArgument:&val atIndex:2];
    [invocation invoke];
}
@end

三、使用

1. 父控制器为竖屏，子控制器为横屏，只需要在自控制器重写三个方法即可。注意需要控制好父、子控制器之间方向的关系。

2. 同一个控制器，需要在竖屏和横屏之间切换，如带有视频播放的控制器。需要重写上面的方法，然后调用[UIDevice setOrientation: orientation] 方法进行屏幕旋转。
   

   这里写图片描述

四、布局

同一控制器在横竖屏之间切换，经常需要不同的布局。在iOS 8及以后的系统可以使用SizeClass方便地部署横竖屏的AutoLayout。在Xcode 8及更高版本后，界面有所改变。

这里写图片描述

所有不是在Vary for Traits 下添加的约束会被当做为所有尺寸的设备添加的约束。
点击Vary for Traits 选择宽高，可以为指定的设备(群)添加约束。

五、方向说明

UIDeviceOrientation 用于表示设备的物理方向

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
} __TVOS_PROHIBITED;

UIInterfaceOrientation 用于表示界面的方向，当设备向右旋转时，UI需要向左旋转，所以在Left和Right两个方向上，UIInterfaceOrientation与UIDeviceOrientation是相反的。

typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
    UIInterfaceOrientationUnknown            = UIDeviceOrientationUnknown,
    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,
    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,
    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,
    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft
}

UIInterfaceOrientationMask ，在单个方向上与UIInterfaceOrientation并无区别，只是多了UIInterfaceOrientationMaskLandscape、UIInterfaceOrientationMaskAll、UIInterfaceOrientationMaskAllButUpsideDown等表示界面方向的集合。

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),
}