//

// UIViewController.h
// UIKit
//
// Copyright (c) 2007-2015 Apple Inc. All rights reserved.
//



#import <Foundation/Foundation.h>
#import <Foundation/NSExtensionRequestHandling.h>
#import <UIKit/UIKitDefines.h>
#import <UIKit/UIApplication.h>
#import <UIKit/UIStateRestoration.h>
#import <UIKit/UITraitCollection.h>
#import <UIKit/UIFocus.h>



/*

 UIViewController is a generic controller base class that manages a view. It has methods that are called
 when a view appears or disappears.
 Subclasses can override -loadView to create their custom view hierarchy, or specify a nib name to be loaded
 automatically. This class is also a good place for delegate & datasource methods, and other controller
 stuff.

*/



NS_ASSUME_NONNULL_BEGIN



@class UIView;
@class UINavigationItem, UIBarButtonItem, UITabBarItem;
@class UISearchDisplayController;
@class UIPopoverController;
@class UIStoryboard, UIStoryboardSegue, UIStoryboardUnwindSegueSource;
@class UIScrollView;
@protocol UIViewControllerTransitionCoordinator;


// modal 过度的样式
typedef NS_ENUM(NSInteger, UIModalTransitionStyle) {

     UIModalTransitionStyleCoverVertical = 0,
     UIModalTransitionStyleFlipHorizontal __TVOS_PROHIBITED,
     UIModalTransitionStyleCrossDissolve,
     UIModalTransitionStylePartialCurl NS_ENUM_AVAILABLE_IOS(3_2) __TVOS_PROHIBITED,
};


// modal 呈现的样式
typedef NS_ENUM(NSInteger, UIModalPresentationStyle) {

     UIModalPresentationFullScreen = 0,
     UIModalPresentationPageSheet NS_ENUM_AVAILABLE_IOS(3_2) __TVOS_PROHIBITED,
     UIModalPresentationFormSheet NS_ENUM_AVAILABLE_IOS(3_2) __TVOS_PROHIBITED,
     UIModalPresentationCurrentContext NS_ENUM_AVAILABLE_IOS(3_2),
     UIModalPresentationCustom NS_ENUM_AVAILABLE_IOS(7_0),
     UIModalPresentationOverFullScreen NS_ENUM_AVAILABLE_IOS(8_0),
     UIModalPresentationOverCurrentContext NS_ENUM_AVAILABLE_IOS(8_0),
     UIModalPresentationPopover NS_ENUM_AVAILABLE_IOS(8_0) __TVOS_PROHIBITED,
     UIModalPresentationNone NS_ENUM_AVAILABLE_IOS(7_0) = -1,
};



// 内容容器协议
@protocol UIContentContainer <NSObject>



@property (nonatomic, readonly) CGSize preferredContentSize NS_AVAILABLE_IOS(8_0);

- (void)preferredContentSizeDidChangeForChildContentContainer:(id <UIContentContainer>)container NS_AVAILABLE_IOS(8_0);


/*

 Intended as a bridge for a view controller that does not use auto layout presenting a child that does use auto layout.
 If the child's view is using auto layout and the -systemLayoutSizeFittingSize: of the view
 changes, -systemLayoutFittingSizeDidChangeForChildContentContainer: will be sent to the view controller's parent.

 */

- (void)systemLayoutFittingSizeDidChangeForChildContentContainer:(id <UIContentContainer>)container NS_AVAILABLE_IOS(8_0);

/*

 When the content container forwards viewWillTransitionToSize:withTransitionCoordinator: to its children, it will call this method to determine what size to send them.

 If the returned size is the same as the child container's current size, viewWillTransitionToSize:withTransitionCoordinator: will not be called.

 */

- (CGSize)sizeForChildContentContainer:(id <UIContentContainer>)container withParentContainerSize:(CGSize)parentSize NS_AVAILABLE_IOS(8_0);



/*
 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);



@end

UIViewController

// Sometimes view controllers that are using showViewController:sender and showDetailViewController:sender: will need to know when the split view controller environment above it has changed. This notification will be posted when that happens (for example, when a split view controller is collapsing or expanding). The NSNotification's object will be the view controller that caused the change.

UIKIT_EXTERN NSString *const UIViewControllerShowDetailTargetDidChangeNotification NS_AVAILABLE_IOS(8_0);



NS_CLASS_AVAILABLE_IOS(2_0) @interface UIViewController : UIResponder <NSCoding, UIAppearanceContainer, UITraitEnvironment, UIContentContainer, UIFocusEnvironment>



/*

 The designated initializer. If you subclass UIViewController, you must call the super implementation of this
 method, even if you aren't using a NIB. (As a convenience, the default init method will do this for you,
 and specify nil for both of this methods arguments.) In the specified NIB, the File's Owner proxy should
 have its class set to your view controller subclass, with the view outlet connected to the main view. If you
 invoke this method with a nil nib name, then this class' -loadView method will attempt to load a NIB whose
 name is the same as your view controller's class. If no such NIB in fact exists then you must either call
 -setView: before -view is invoked, or override the -loadView method to set up your views programatically.

*/

// 初始化方法
- (instancetype)initWithNibName:(nullable NSString *)nibNameOrNil bundle:(nullable NSBundle *)nibBundleOrNil NS_DESIGNATED_INITIALIZER;

- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;


// 控制绑定的 view
@property(null_resettable, nonatomic,strong) UIView *view; // The getter first invokes [self loadView] if the view hasn't been set yet. Subclasses must call super if they override the setter or getter.


// 加载视图
// This is where subclasses should create their custom view hierarchy if they aren't using a nib. Should never be called directly.
- (void)loadView; 

// 间接调用 loadView 方法
// Loads the view controller's view if it has not already been set.
- (void)loadViewIfNeeded NS_AVAILABLE_IOS(9_0); 


// Returns the view controller's view if loaded, nil if not.
@property(nullable, nonatomic, readonly, strong) UIView *viewIfLoaded NS_AVAILABLE_IOS(9_0); 


// 视图将要卸载
- (void)viewWillUnload NS_DEPRECATED_IOS(5_0,6_0) __TVOS_PROHIBITED;

// 视图已经卸载
// Called after the view controller's view is released and set to nil. For example, a memory warning which causes the view to be purged. Not invoked as a result of -dealloc.
- (void)viewDidUnload NS_DEPRECATED_IOS(3_0,6_0) __TVOS_PROHIBITED; 


// 视图加载完毕
// Called after the view has been loaded. For view controllers created in code, this is after -loadView. For view controllers unarchived from a nib, this is after the view is set.
- (void)viewDidLoad; 

// 视图是否已经加载
- (BOOL)isViewLoaded NS_AVAILABLE_IOS(3_0);


// xib 的名称
@property(nullable, nonatomic, readonly, copy) NSString *nibName; // The name of the nib to be loaded to instantiate the view.

// xib 的资源文件
@property(nullable, nonatomic, readonly, strong) NSBundle *nibBundle; // The bundle from which to load the nib.

// 实例化控制器是 xb 对象
@property(nullable, nonatomic, readonly, strong) UIStoryboard *storyboard NS_AVAILABLE_IOS(5_0);


// 执行 segue
- (void)performSegueWithIdentifier:(NSString *)identifier sender:(nullable id)sender NS_AVAILABLE_IOS(5_0);

// 将要执行 segue
// Invoked immediately prior to initiating a segue. Return NO to prevent the segue from firing. The default implementation returns YES. This method is not invoked when -performSegueWithIdentifier:sender: is used.
- (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(nullable id)sender NS_AVAILABLE_IOS(6_0); 


// 准备执行 segue
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(nullable id)sender NS_AVAILABLE_IOS(5_0);



// View controllers will receive this message during segue unwinding. The default implementation returns the result of -respondsToSelector: - controllers can override this to perform any ancillary checks, if necessary.
// 能够执行 松开 segue
- (BOOL)canPerformUnwindSegueAction:(SEL)action fromViewController:(UIViewController *)fromViewController withSender:(id)sender NS_AVAILABLE_IOS(6_0);



// Returns a subset of the receiver's childViewControllers in the order they should be searched for an unwind destination.

// The default implementation first sends itself -childViewControllerContainingSegueSource:, then returns a copy of its childViewControllers array excluding that object. A custom container view controller can override this method to affect the order in which its children are searched, or to modify the result of the default implementation.

// For compatibility, if a view controller overrides the deprecated -viewControllerForUnwindSegueAction:fromViewController:sender: method, but does not override this method, it will receive the deprecated method instead of this method.

// To affect this view controller's eligibility as an unwind destination, override -canPerformUnwindSegueAction:fromViewController:withSender: instead.
// 允许自控制执行 松开 segue
- (NSArray<UIViewController *> *)allowedChildViewControllersForUnwindingFromSource:(UIStoryboardUnwindSegueSource *)source NS_AVAILABLE_IOS(9_0);



// Returns the child view controller that contains the provided segue source.

// Custom container view controllers should call this method from their implementation of -allowedChildViewControllersForUnwindingFromSource: to exclude the result from the returned array, as well as to determine the order of the returned array's contents.

// Do not try to re-implement or override this method; it takes special care to handle situations such as unwinding from a modally-presented view controller.
// 子视图控制器包含的 segue 源控
- (nullable UIViewController *)childViewControllerContainingSegueSource:(UIStoryboardUnwindSegueSource *)source NS_AVAILABLE_IOS(9_0);



// Deprecated. Returns a direct child of the receiver that responds YES to -canPerformUnwindSegueAction:fromViewController:withSender:, or self if no children respond YES but the receiver itself does. If this method has been overridden, UIViewController's implementation does not consult child view controllers at all, and skips straight to sending -canPerformUnwindSegueAction:... to self.

- (nullable UIViewController *)viewControllerForUnwindSegueAction:(SEL)action fromViewController:(UIViewController *)fromViewController withSender:(nullable id)sender NS_DEPRECATED_IOS(6_0, 9_0);



// Custom container view controllers should override this method to modify themselves as part of an ongoing unwind segue. The subsequentVC is the parent, child, or presented view controller closest to the receiver in the direction of the segue's destinationViewController. For example, UINavigationController's implementation of this method will pop any necessary view controllers to reveal the subsequentVC.

- (void)unwindForSegue:(UIStoryboardSegue *)unwindSegue towardsViewController:(UIViewController *)subsequentVC NS_AVAILABLE_IOS(9_0);



// Deprecated. Returns a segue that will unwind from the source to destination view controller via the -unwindForSegue:towardViewController: method. When performing an unwind segue defined in a storyboard, if any view controller along the unwind path has overridden this method and returns non-nil, the runtime will use that segue object instead of constructing an instance of the class specified in Interface Builder.

- (nullable UIStoryboardSegue *)segueForUnwindingToViewController:(UIViewController *)toViewController fromViewController:(UIViewController *)fromViewController identifier:(nullable NSString *)identifier NS_DEPRECATED_IOS(6_0, 9_0);





// 视图将要显示
- (void)viewWillAppear:(BOOL)animated; // Called when the view is about to made visible. Default does nothing


// 视图已经显示
- (void)viewDidAppear:(BOOL)animated; // Called when the view has been fully transitioned onto the screen. Default does nothing


// 视图将要消失
- (void)viewWillDisappear:(BOOL)animated; // Called when the view is dismissed, covered or otherwise hidden. Default does nothing


// 视图已经消失
- (void)viewDidDisappear:(BOOL)animated; // Called after the view was dismissed, covered or otherwise hidden. Default does nothing



// Called just before the view controller's view's layoutSubviews method is invoked. Subclasses can implement as necessary. The default is a nop.
// 视图将要布局子控件
- (void)viewWillLayoutSubviews NS_AVAILABLE_IOS(5_0);

// Called just after the view controller's view's layoutSubviews method is invoked. Subclasses can implement as necessary. The default is a nop.
// 视图已经布局完子控件
- (void)viewDidLayoutSubviews NS_AVAILABLE_IOS(5_0);


// 控制器标题
@property(nullable, nonatomic,copy) NSString *title; // Localized title for use by a parent controller.


// 收到内存警告
- (void)didReceiveMemoryWarning; // Called when the parent application receives a memory warning. On iOS 6.0 it will no longer clear the view by default.



/*

 If this view controller is a child of a containing view controller (e.g. a navigation controller or tab bar

 controller,) this is the containing view controller. Note that as of 5.0 this no longer will return the

 presenting view controller.

*/
// 父控制器
@property(nullable,nonatomic,weak,readonly) UIViewController *parentViewController;



// This property has been replaced by presentedViewController.
// modal 控制器

@property(nullable, nonatomic,readonly) UIViewController *modalViewController NS_DEPRECATED_IOS(2_0, 6_0) __TVOS_PROHIBITED;



// The view controller that was presented by this view controller or its nearest ancestor.
// 已经显示的控制器
@property(nullable, nonatomic,readonly) UIViewController *presentedViewController NS_AVAILABLE_IOS(5_0);



// The view controller that presented this view controller (or its farthest ancestor.)
// 正在显示的控制器
@property(nullable, nonatomic,readonly) UIViewController *presentingViewController NS_AVAILABLE_IOS(5_0);



/*

 Determines which parent view controller's view should be presented over for presentations of type
 UIModalPresentationCurrentContext. If no ancestor view controller has this flag set, then the presenter
 will be the root view controller.
*/
// 是否定义呈现的上下文
@property(nonatomic,assign) BOOL definesPresentationContext NS_AVAILABLE_IOS(5_0);



// A controller that defines the presentation context can also specify the modal transition style if this property is true.
// 是否提供呈现上下文转场的样式
@property(nonatomic,assign) BOOL providesPresentationContextTransitionStyle NS_AVAILABLE_IOS(5_0);



/*

 These four methods can be used in a view controller's appearance callbacks to determine if it is being
 presented, dismissed, or added or removed as a child view controller. For example, a view controller can
 check if it is disappearing because it was dismissed or popped by asking itself in its viewWillDisappear:
 method by checking the expression ([self isBeingDismissed] || [self isMovingFromParentViewController]).
*/


// 是否开始显示
- (BOOL)isBeingPresented NS_AVAILABLE_IOS(5_0);

// 是否开始消失
- (BOOL)isBeingDismissed NS_AVAILABLE_IOS(5_0);



- (BOOL)isMovingToParentViewController NS_AVAILABLE_IOS(5_0);

- (BOOL)isMovingFromParentViewController NS_AVAILABLE_IOS(5_0);



/*

 The next two methods are replacements for presentModalViewController:animated and
 dismissModalViewControllerAnimated: The completion handler, if provided, will be invoked after the presented
 controllers viewDidAppear: callback is invoked.
*/
// 呈现控制器
- (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^ __nullable)(void))completion NS_AVAILABLE_IOS(5_0);

// The completion handler, if provided, will be invoked after the dismissed controller's viewDidDisappear: callback is invoked.
// 消失控制器
- (void)dismissViewControllerAnimated: (BOOL)flag completion: (void (^ __nullable)(void))completion NS_AVAILABLE_IOS(5_0);



// Display another view controller as a modal child. Uses a vertical sheet transition if animated.This method has been replaced by presentViewController:animated:completion:
// 呈现一个 modal 的控制器
- (void)presentModalViewController:(UIViewController *)modalViewController animated:(BOOL)animated NS_DEPRECATED_IOS(2_0, 6_0) __TVOS_PROHIBITED;



// Dismiss the current modal child. Uses a vertical sheet transition if animated. This method has been replaced by dismissViewControllerAnimated:completion:
// 消失一个 modal 的控制器
- (void)dismissModalViewControllerAnimated:(BOOL)animated NS_DEPRECATED_IOS(2_0, 6_0) __TVOS_PROHIBITED;


/*

 Defines the transition style that will be used for this view controller when it is presented modally. Set
 this property on the view controller to be presented, not the presenter. Defaults to
 UIModalTransitionStyleCoverVertical.
*/
// moda 过度的样式
@property(nonatomic,assign) UIModalTransitionStyle modalTransitionStyle NS_AVAILABLE_IOS(3_0);


// modal的呈现的样式
@property(nonatomic,assign) UIModalPresentationStyle modalPresentationStyle NS_AVAILABLE_IOS(3_2);

// This controls whether this view controller takes over control of the status bar's appearance when presented non-full screen on another view controller. Defaults to NO.
// moda 呈现的时候是否捕获状态栏的外观
@property(nonatomic,assign) BOOL modalPresentationCapturesStatusBarAppearance NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;



// Presentation modes may keep the keyboard visible when not required. Default implementation affects UIModalPresentationFormSheet visibility.

- (BOOL)disablesAutomaticKeyboardDismissal NS_AVAILABLE_IOS(4_3);


// 是否需要满屏的布局
@property(nonatomic,assign) BOOL wantsFullScreenLayout NS_DEPRECATED_IOS(3_0, 7_0) __TVOS_PROHIBITED; // Deprecated in 7_0, Replaced by the following:


// 延展布局的边缘
@property(nonatomic,assign) UIRectEdge edgesForExtendedLayout NS_AVAILABLE_IOS(7_0); // Defaults to UIRectEdgeAll


// 延展布局包含不透明的栏
@property(nonatomic,assign) BOOL extendedLayoutIncludesOpaqueBars NS_AVAILABLE_IOS(7_0); // Defaults to NO, but bars are translucent by default on 7_0.


// 自动调整滚动视图的外边距
@property(nonatomic,assign) BOOL automaticallyAdjustsScrollViewInsets NS_AVAILABLE_IOS(7_0); // Defaults to YES



/* The preferredContentSize is used for any container laying out a child view controller.

 */
// 首选的内容尺寸
@property (nonatomic) CGSize preferredContentSize NS_AVAILABLE_IOS(7_0);



// These methods control the attributes of the status bar when this view controller is shown. They can be overridden in view controller subclasses to return the desired status bar attributes.

// 设置状态栏的样式
- (UIStatusBarStyle)preferredStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to UIStatusBarStyleDefault

// 隐藏状态栏
- (BOOL)prefersStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to NO

// Override to return the type of animation that should be used for status bar changes for this view controller. This currently only affects changes to prefersStatusBarHidden.
// 更新状态栏的样式
- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to UIStatusBarAnimationFade



// This should be called whenever the return values for the view controller's status bar attributes have changed. If it is called from within an animation block, the changes will be animated along with the rest of the animation block.

- (void)setNeedsStatusBarAppearanceUpdate NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;



/* This method returns either itself or the nearest ancestor that can perform the given action and, if applicable, has overridden UIViewController's default implementation of the action method. View controllers can return NO from canPerformAction:withSender: to opt out of being a target for a given action. */
// 目标视图控制器
- (nullable UIViewController *)targetViewControllerForAction:(SEL)action sender:(nullable id)sender NS_AVAILABLE_IOS(8_0);



/* This method will show a view controller appropriately for the current size-class environment. It's implementation calls

 `[self targetViewControllerForAction:sender:]` first and redirects accordingly if the return value is not `self`, otherwise it will present the vc. */
// 显示控制器
- (void)showViewController:(UIViewController *)vc sender:(nullable id)sender NS_AVAILABLE_IOS(8_0);



/* This method will show a view controller within the semantic "detail" UI associated with the current size-class environment. It's implementation calls `[self targetViewControllerForAction:sender:]` first and redirects accordingly if the return value is not `self`, otherwise it will present the vc. */
// 显示详细控制器
- (void)showDetailViewController:(UIViewController *)vc sender:(nullable id)sender NS_AVAILABLE_IOS(8_0);



@end

视图控制器的旋转

// To make it more convenient for applications to adopt rotation, a view controller may implement the below methods. Your UIWindow's frame should use [UIScreen mainScreen].bounds as its frame.

@interface UIViewController (UIViewControllerRotation)


// 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 NS_AVAILABLE_IOS(5_0) __TVOS_PROHIBITED;



// Applications should use supportedInterfaceOrientations and/or shouldAutorotate..
// 将要自动旋转到界面的方向
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation NS_DEPRECATED_IOS(2_0, 6_0) __TVOS_PROHIBITED;



// New Autorotation support.
// 是否支持自动旋转
- (BOOL)shouldAutorotate NS_AVAILABLE_IOS(6_0) __TVOS_PROHIBITED;

// 支持自动旋转的方向
- (UIInterfaceOrientationMask)supportedInterfaceOrientations NS_AVAILABLE_IOS(6_0) __TVOS_PROHIBITED;

// Returns interface orientation masks.
// 偏好的界面方向
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation NS_AVAILABLE_IOS(6_0) __TVOS_PROHIBITED;



// The rotating header and footer views will slide out during the rotation and back in once it has completed.

- (nullable UIView *)rotatingHeaderView NS_DEPRECATED_IOS(2_0,8_0, "Header views are animated along with the rest of the view hierarchy") __TVOS_PROHIBITED; 
// Must be in the view hierarchy. Default returns nil.

- (nullable UIView *)rotatingFooterView NS_DEPRECATED_IOS(2_0,8_0, "Footer views are animated along with the rest of the view hierarchy") __TVOS_PROHIBITED; 
// Must be in the view hierarchy. Default returns nil.


// 界面方向
@property(nonatomic,readonly) UIInterfaceOrientation interfaceOrientation NS_DEPRECATED_IOS(2_0,8_0) __TVOS_PROHIBITED;



// Notifies when rotation begins, reaches halfway point and ends.

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration NS_DEPRECATED_IOS(2_0,8_0, "Implement viewWillTransitionToSize:withTransitionCoordinator: instead") __TVOS_PROHIBITED;

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation NS_DEPRECATED_IOS(2_0,8_0) __TVOS_PROHIBITED;



- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration NS_DEPRECATED_IOS(3_0,8_0, "Implement viewWillTransitionToSize:withTransitionCoordinator: instead") __TVOS_PROHIBITED;



- (void)willAnimateFirstHalfOfRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration NS_DEPRECATED_IOS(2_0, 5_0) __TVOS_PROHIBITED;

- (void)didAnimateFirstHalfOfRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation NS_DEPRECATED_IOS(2_0, 5_0) __TVOS_PROHIBITED; // The rotating header and footer views are offscreen.

- (void)willAnimateSecondHalfOfRotationFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation duration:(NSTimeInterval)duration NS_DEPRECATED_IOS(2_0, 5_0) __TVOS_PROHIBITED; // A this point, our view orientation is set to the new orientation.



@end



// Many view controllers have a view that may be in an editing state or not- for example, a UITableView. These view

// controllers can track the editing state, and generate an Edit|Done button to be used in a navigation bar.

@interface UIViewController (UIViewControllerEditing)



@property(nonatomic,getter=isEditing) BOOL editing;

- (void)setEditing:(BOOL)editing animated:(BOOL)animated; // Updates the appearance of the Edit|Done button item as necessary. Clients who override it must call super first.



- (UIBarButtonItem *)editButtonItem; // Return an Edit|Done button that can be used as a navigation item's custom view. Default action toggles the editing state with animation.



@end



@interface UIViewController (UISearchDisplayControllerSupport)



@property(nullable, nonatomic, readonly, strong) UISearchDisplayController *searchDisplayController NS_DEPRECATED_IOS(3_0,8_0) __TVOS_PROHIBITED;



@end





/*

 This exception is raised when a child view controller's view is added into the view hierarchy and the first

 superview of the child view controller's view that has a view controller is NOT the child view controller's

 parent.

*/

UIKIT_EXTERN NSString *const UIViewControllerHierarchyInconsistencyException NS_AVAILABLE_IOS(5_0);



/*

 The methods in the UIContainerViewControllerProtectedMethods and the UIContainerViewControllerCallbacks

 categories typically should only be called by subclasses which are implementing new container view

 controllers. They may be overridden but must call super.

*/

@interface UIViewController (UIContainerViewControllerProtectedMethods)



// An array of children view controllers. This array does not include any presented view controllers.

@property(nonatomic,readonly) NSArray<__kindof UIViewController *> *childViewControllers NS_AVAILABLE_IOS(5_0);



/*

 If the child controller has a different parent controller, it will first be removed from its current parent

 by calling removeFromParentViewController. If this method is overridden then the super implementation must

 be called.

*/

- (void)addChildViewController:(UIViewController *)childController NS_AVAILABLE_IOS(5_0);



/*

 Removes the the receiver from its parent's children controllers array. If this method is overridden then

 the super implementation must be called.

*/

- (void) removeFromParentViewController NS_AVAILABLE_IOS(5_0);



/*

 This method can be used to transition between sibling child view controllers. The receiver of this method is

 their common parent view controller. (Use [UIViewController addChildViewController:] to create the

 parent/child relationship.) This method will add the toViewController's view to the superview of the

 fromViewController's view and the fromViewController's view will be removed from its superview after the

 transition completes. It is important to allow this method to add and remove the views. The arguments to

 this method are the same as those defined by UIView's block animation API. This method will fail with an

 NSInvalidArgumentException if the parent view controllers are not the same as the receiver, or if the

 receiver explicitly forwards its appearance and rotation callbacks to its children. Finally, the receiver

 should not be a subclass of an iOS container view controller. Note also that it is possible to use the

 UIView APIs directly. If they are used it is important to ensure that the toViewController's view is added

 to the visible view hierarchy while the fromViewController's view is removed.

*/

- (void)transitionFromViewController:(UIViewController *)fromViewController toViewController:(UIViewController *)toViewController duration:(NSTimeInterval)duration options:(UIViewAnimationOptions)options animations:(void (^ __nullable)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(5_0);



// If a custom container controller manually forwards its appearance callbacks, then rather than calling

// viewWillAppear:, viewDidAppear: viewWillDisappear:, or viewDidDisappear: on the children these methods

// should be used instead. This will ensure that descendent child controllers appearance methods will be

// invoked. It also enables more complex custom transitions to be implemented since the appearance callbacks are

// now tied to the final matching invocation of endAppearanceTransition.

- (void)beginAppearanceTransition:(BOOL)isAppearing animated:(BOOL)animated __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_5_0);

- (void)endAppearanceTransition __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_5_0);



// Override to return a child view controller or nil. If non-nil, that view controller's status bar appearance attributes will be used. If nil, self is used. Whenever the return values from these methods change, -setNeedsUpdatedStatusBarAttributes should be called.

- (nullable UIViewController *)childViewControllerForStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;

- (nullable UIViewController *)childViewControllerForStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;



// Call to modify the trait collection for child view controllers.

- (void)setOverrideTraitCollection:(nullable UITraitCollection *)collection forChildViewController:(UIViewController *)childViewController NS_AVAILABLE_IOS(8_0);

- (nullable UITraitCollection *)overrideTraitCollectionForChildViewController:(UIViewController *)childViewController NS_AVAILABLE_IOS(8_0);



@end



@interface UIViewController (UIContainerViewControllerCallbacks)



/*

 This method is consulted to determine if a view controller manually forwards its containment callbacks to

 any children view controllers. Subclasses of UIViewController that implement containment logic may override

 this method. The default implementation returns YES. If it is overridden and returns NO, then the subclass is

 responsible for forwarding the following methods as appropriate - viewWillAppear: viewDidAppear: viewWillDisappear:

 viewDidDisappear: willRotateToInterfaceOrientation:duration:

 willAnimateRotationToInterfaceOrientation:duration: didRotateFromInterfaceOrientation:

*/



- (BOOL)automaticallyForwardAppearanceAndRotationMethodsToChildViewControllers NS_DEPRECATED_IOS(5_0,6_0) __TVOS_PROHIBITED;

- (BOOL)shouldAutomaticallyForwardRotationMethods NS_DEPRECATED_IOS(6_0,8_0, "Manually forward viewWillTransitionToSize:withTransitionCoordinator: if necessary") __TVOS_PROHIBITED;



- (BOOL)shouldAutomaticallyForwardAppearanceMethods NS_AVAILABLE_IOS(6_0);





/*

 These two methods are public for container subclasses to call when transitioning between child

 controllers. If they are overridden, the overrides should ensure to call the super. The parent argument in

 both of these methods is nil when a child is being removed from its parent; otherwise it is equal to the new

 parent view controller.



 addChildViewController: will call [child willMoveToParentViewController:self] before adding the

 child. However, it will not call didMoveToParentViewController:. It is expected that a container view

 controller subclass will make this call after a transition to the new child has completed or, in the

 case of no transition, immediately after the call to addChildViewController:. Similarly

 removeFromParentViewController: does not call [self willMoveToParentViewController:nil] before removing the

 child. This is also the responsibilty of the container subclass. Container subclasses will typically define

 a method that transitions to a new child by first calling addChildViewController:, then executing a

 transition which will add the new child's view into the view hierarchy of its parent, and finally will call

 didMoveToParentViewController:. Similarly, subclasses will typically define a method that removes a child in

 the reverse manner by first calling [child willMoveToParentViewController:nil].

*/

- (void)willMoveToParentViewController:(nullable UIViewController *)parent NS_AVAILABLE_IOS(5_0);

- (void)didMoveToParentViewController:(nullable UIViewController *)parent NS_AVAILABLE_IOS(5_0);



@end



@interface UIViewController (UIStateRestoration) <UIStateRestoring>

@property (nullable, nonatomic, copy) NSString *restorationIdentifier NS_AVAILABLE_IOS(6_0);

@property (nullable, nonatomic, readwrite, assign) Class<UIViewControllerRestoration> restorationClass NS_AVAILABLE_IOS(6_0);

- (void) encodeRestorableStateWithCoder:(NSCoder *)coder NS_AVAILABLE_IOS(6_0);

- (void) decodeRestorableStateWithCoder:(NSCoder *)coder NS_AVAILABLE_IOS(6_0);

- (void) applicationFinishedRestoringState NS_AVAILABLE_IOS(7_0);

@end



@interface UIViewController (UIConstraintBasedLayoutCoreMethods)

/* Base implementation sends -updateConstraints to the view.

 When a view has a view controller, this message is sent to the view controller during

 the autolayout updateConstraints pass in lieu of sending updateConstraints directly

 to the view.

 You may override this method in a UIViewController subclass for updating custom

 constraints instead of subclassing your view and overriding -[UIView updateConstraints].

 Overrides must call super or send -updateConstraints to the view.

 */

- (void)updateViewConstraints NS_AVAILABLE_IOS(6_0);

@end



@protocol UIViewControllerTransitioningDelegate;



@interface UIViewController(UIViewControllerTransitioning)



@property (nullable, nonatomic, weak) id <UIViewControllerTransitioningDelegate> transitioningDelegate NS_AVAILABLE_IOS(7_0);



@end



@interface UIViewController (UILayoutSupport)

// These objects may be used as layout items in the NSLayoutConstraint API

@property(nonatomic,readonly,strong) id<UILayoutSupport> topLayoutGuide NS_AVAILABLE_IOS(7_0);

@property(nonatomic,readonly,strong) id<UILayoutSupport> bottomLayoutGuide NS_AVAILABLE_IOS(7_0);

@end



@interface UIViewController (UIKeyCommand)



- (void)addKeyCommand:(UIKeyCommand *)keyCommand NS_AVAILABLE_IOS(9_0);

- (void)removeKeyCommand:(UIKeyCommand *)keyCommand NS_AVAILABLE_IOS(9_0);



@end



@class NSExtensionContext;



@interface UIViewController(NSExtensionAdditions) <NSExtensionRequestHandling>



// Returns the extension context. Also acts as a convenience method for a view controller to check if it participating in an extension request.

@property (nullable, nonatomic,readonly,strong) NSExtensionContext *extensionContext NS_AVAILABLE_IOS(8_0);



@end



@class UIPresentationController, UIPopoverPresentationController;



@interface UIViewController (UIAdaptivePresentations)

@property (nullable, nonatomic,readonly) UIPresentationController *presentationController NS_AVAILABLE_IOS(8_0);

@property (nullable, nonatomic,readonly) UIPopoverPresentationController *popoverPresentationController NS_AVAILABLE_IOS(8_0);

@end





@protocol UIViewControllerPreviewingDelegate;



@protocol UIViewControllerPreviewing <NSObject>



// This gesture can be used to cause the previewing presentation to wait until one of your gestures fails or to allow simultaneous recognition during the initial phase of the preview presentation.

@property (nonatomic, readonly) UIGestureRecognizer *previewingGestureRecognizerForFailureRelationship NS_AVAILABLE_IOS(9_0);



@property (nonatomic, readonly) id<UIViewControllerPreviewingDelegate> delegate NS_AVAILABLE_IOS(9_0);

@property (nonatomic, readonly) UIView *sourceView NS_AVAILABLE_IOS(9_0);



// This rect will be set to the bounds of sourceView before each call to

// -previewingContext:viewControllerForLocation:



@property (nonatomic) CGRect sourceRect NS_AVAILABLE_IOS(9_0);



@end





NS_CLASS_AVAILABLE_IOS(9_0) @protocol UIViewControllerPreviewingDelegate <NSObject>



// If you return nil, a preview presentation will not be performed

- (nullable UIViewController *)previewingContext:(id <UIViewControllerPreviewing>)previewingContext viewControllerForLocation:(CGPoint)location NS_AVAILABLE_IOS(9_0);

- (void)previewingContext:(id <UIViewControllerPreviewing>)previewingContext commitViewController:(UIViewController *)viewControllerToCommit NS_AVAILABLE_IOS(9_0);



@end



@interface UIViewController (UIViewControllerPreviewingRegistration)



// Registers a view controller to participate with 3D Touch preview (peek) and commit (pop).

- (id <UIViewControllerPreviewing>)registerForPreviewingWithDelegate:(id<UIViewControllerPreviewingDelegate>)delegate sourceView:(UIView *)sourceView NS_AVAILABLE_IOS(9_0);

- (void)unregisterForPreviewingWithContext:(id <UIViewControllerPreviewing>)previewing NS_AVAILABLE_IOS(9_0);



@end



@protocol UIPreviewActionItem;



@interface UIViewController ()



- (NSArray <id <UIPreviewActionItem>> *)previewActionItems NS_AVAILABLE_IOS(9_0);



@end





NS_CLASS_AVAILABLE_IOS(9_0) @protocol UIPreviewActionItem <NSObject>

@property(nonatomic, copy, readonly) NSString *title;

@end



typedef NS_ENUM(NSInteger,UIPreviewActionStyle) {

 UIPreviewActionStyleDefault=0,

 UIPreviewActionStyleSelected,

 UIPreviewActionStyleDestructive,

} NS_ENUM_AVAILABLE_IOS(9_0);



NS_CLASS_AVAILABLE_IOS(9_0) @interface UIPreviewAction : NSObject <NSCopying,UIPreviewActionItem>



@property(nonatomic, copy, readonly) void (^handler)(id<UIPreviewActionItem> action, UIViewController *previewViewController);



+ (instancetype)actionWithTitle:(NSString *)title style:(UIPreviewActionStyle)style handler:(void (^)(UIPreviewAction *action, UIViewController *previewViewController))handler;



@end



NS_CLASS_AVAILABLE_IOS(9_0) @interface UIPreviewActionGroup : NSObject <NSCopying,UIPreviewActionItem>

+ (instancetype)actionGroupWithTitle:(NSString *)title style:(UIPreviewActionStyle)style actions:(NSArray<UIPreviewAction *> *)actions;

@end



NS_ASSUME_NONNULL_END