Device Orientation：設備方向

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
}

UIInterfaceOrientation：界面方向

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

屏幕旋轉的兩個通知

// 硬件旋轉通知，此時界面還未完成旋轉可設置界面的旋轉
UIDeviceOrientationDidChangeNotification
// 界面旋轉通知，此時界面已經(jīng)完成旋轉
UIApplicationDidChangeStatusBarOrientationNotification

判斷當前界面方向

BOOL isPortrait = UIInterfaceOrientationIsPortrait([[UIApplication sharedApplication] statusBarOrientation]);
BOOL isLandscape = UIInterfaceOrientationIsLandscape([[UIApplication sharedApplication] statusBarOrientation]);

單個頁面是否可以旋轉

@property(nonatomic, readonly) BOOL shouldAutorotate NS_AVAILABLE_IOS(6_0) __TVOS_PROHIBITED;
@property(nonatomic, readonly) UIInterfaceOrientationMask supportedInterfaceOrientations NS_AVAILABLE_IOS(6_0) __TVOS_PROHIBITED;

• 面向Orientation的信息：隨著屏幕的方向變化

  • [UISCreen bounds]
  • [UISCreen applicationFrame]
  • Status bar frame notifications
  • Keyboard frame notifications

• 屏幕旋轉時使得View有不同布局的實現(xiàn)方法

// way1
- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator {
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
    [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        if (UIInterfaceOrientationIsPortrait([UIApplication sharedApplication].statusBarOrientation)) {
            _testTextField.frame = CGRectMake(50, 50, 150, 50);
            _testButton.frame = CGRectMake(50, 120, 150, 50);
        } else {
            _testTextField.frame = CGRectMake(50, 50, 150, 50);
            _testButton.frame = CGRectMake(220, 50, 150, 50);
        }
    } completion:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        
    }];
}

// way2
- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    if (UIInterfaceOrientationIsPortrait([UIApplication sharedApplication].statusBarOrientation)) {
        _testTextField.frame = CGRectMake(50, 50, 150, 50);
        _testButton.frame = CGRectMake(50, 120, 150, 50);
    } else {
        _testTextField.frame = CGRectMake(50, 50, 150, 50);
        _testButton.frame = CGRectMake(220, 50, 150, 50);
    }
}

• 旋轉屏幕方向

NSNumber *value0 = [NSNumber numberWithInteger:UIDeviceOrientationUnknown];
[[UIDevice currentDevice] setValue:value0 forKey:@"orientation"];
NSNumber *value = [NSNumber numberWithInteger:UIDeviceOrientationLandscapeLeft];
[[UIDevice currentDevice] setValue:value forKey:@"orientation"];

• 需求：APP總體不跟隨設備的旋轉來改變界面的方向，個別頁面橫屏展示

實現(xiàn)思路：首先APP應該支持橫屏和豎屏的展示狞谱，也就是說在TARGETS中的Device Orientation選項勾選橫屏和豎屏選項瞎领。假設ViewController是根視圖挟阻，那么當ViewController的- (BOOL)shouldAutorotate方法返回為YES的時候毅整，界面的方向跟隨設備方向變化。在NV結構（NavigationController上放置ViewController的結構）中需橫屏展示的ViewController可不是根視圖木羹，此時界面是否跟隨設備旋轉取決于根視圖NavigationController的- (BOOL)shouldAutorotate方法的返回值。在這種情況中解孙，可重寫NavigationController的- (BOOL)shouldAutorotate方法返回Navigation棧中的頂部ViewController的shouldAutorotate坑填，以此達到在單個頁面隨時控制其橫屏的效果。橫屏通過Key-Value的方法修改設備方向來達到目的弛姜。

一脐瑰、勾選橫屏和豎屏選項

勾選橫屏和豎屏選項

二、重寫- (BOOL)shouldAutorotate返回棧頂控制器的shouldAutorotate

@interface MyNav : UINavigationController

@end

@implementation MyNav

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

@end

三廷臼、在將要橫屏顯示的ViewController中苍在，重寫- (BOOL)shouldAutorotate绝页，重點是用全局變量控制它的返回值

@interface LandscapeViewController () {
    BOOL _allowAutorotate;
}

- (BOOL)shouldAutorotate {
    [super shouldAutorotate];
    return _allowAutorotate;
}

四、通過Key-Value改變設備方向

_allowAutorotate = YES;
NSNumber *value0 = [NSNumber numberWithInteger:UIDeviceOrientationUnknown];
[[UIDevice currentDevice] setValue:value0 forKey:@"orientation"];
NSNumber *value = [NSNumber numberWithInteger:UIDeviceOrientationLandscapeLeft];
[[UIDevice currentDevice] setValue:value forKey:@"orientation"];
_allowAutorotate = NO;