iOS开发UIResponder之NSUndoManager

1、简介

UIResponder有个属性：NSUndoManager

 @property(nullable, nonatomic,readonly) NSUndoManager *undoManager NS_AVAILABLE_IOS(3_0);

NSUndoManager可以叫做撤销管理器，可以撤销和重做，类似快捷键command+z和command+shift+z；
NSUndoManger内部维护两个栈，undo栈（撤销）和redo栈（重写）。

2、NSUndoManger的简单使用

2.1、数组的undo和redo

代码：

#import "UndoTest.h"

@interface UndoTest()
@end
@implementation UndoTest

- (instancetype)init{
    if (self = [super init]) {
        self.undoManager = [[NSUndoManager alloc] init];
        self.undoArr = [NSMutableArray array];
    }
    return self;
}
- (void)addObjectMethod:(NSString *)anObject{
    [[self.undoManager prepareWithInvocationTarget:self] removeObjectMehtod:anObject];
    [self.undoArr addObject:anObject];
}
- (void)removeObjectMehtod:(NSString *)anObject{
    [[self.undoManager prepareWithInvocationTarget:self] addObjectMethod:anObject];
    if ([self.undoArr containsObject:anObject]) {
        [self.undoArr removeObject:anObject];
    }
}

@end

UndoTest代码

效果：

2.2、视图移动的undo和redo

代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    _undoManager = [[NSUndoManager alloc] init];
}
- (void)btnViewAdd{
    [[_undoManager prepareWithInvocationTarget:self] btnViewReduce];
    CGRect rect = self.btnView.frame;
    rect.origin.x +=10;
    self.btnView.frame = rect;
}
- (void)btnViewReduce{
    [[_undoManager prepareWithInvocationTarget:self] btnViewAdd];
    CGRect rect = self.btnView.frame;
    rect.origin.x -=10;
    self.btnView.frame = rect;
}
- (IBAction)addClick:(id)sender {
    [self btnViewAdd];
}
- (IBAction)reduceClick:(id)sender {
    [self btnViewReduce];
}

- (IBAction)undoClick:(UIButton *)sender {
    [_undoManager undo];
}
- (IBAction)redoClick:(UIButton *)sender {
    [_undoManager redo];
}

视图移动代码

效果：

3、NSUndoManger的相关API

NS_CLASS_AVAILABLE(10_0, 3_0)
@interface NSUndoManager : NSObject {
@private
    id             _undoStack;
    id             _redoStack;
    NSArray         *_runLoopModes;
    uint64_t        _NSUndoManagerPrivate1;
    id             _target;
    id            _proxy;
    void        *_NSUndoManagerPrivate2;
    void        *_NSUndoManagerPrivate3;
}

//创建撤销组
- (void)beginUndoGrouping;  //开始
- (void)endUndoGrouping;    //结束
@property BOOL groupsByEvent; //默认启用，自动分组，一个RunLoop事件中注册的所有undomanager为一个顶级组
@property (readonly) NSInteger groupingLevel;//组等级

//启用和禁用撤消
- (void)disableUndoRegistration;
- (void)enableUndoRegistration;
@property (readonly, getter=isUndoRegistrationEnabled) BOOL undoRegistrationEnabled;

/* Groups By Event */


//限制撤销堆栈
@property NSUInteger levelsOfUndo;

//在运行循环的周期内处理输入类型的模式。
@property (copy) NSArray<NSRunLoopMode> *runLoopModes;

//执行撤消和重做
- (void)undo;
- (void)redo;
- (void)undoNestedGroup;

//检查撤销能力
@property (readonly) BOOL canUndo;
@property (readonly) BOOL canRedo;

//检查是否正在执行撤消或重做
@property (readonly, getter=isUndoing) BOOL undoing;
@property (readonly, getter=isRedoing) BOOL redoing;

//移除撤销操作
- (void)removeAllActions;
- (void)removeAllActionsWithTarget:(id)target;

//注册撤消操作
- (void)registerUndoWithTarget:(id)target selector:(SEL)selector object:(nullable id)anObject;
- (id)prepareWithInvocationTarget:(id)target;
- (void)registerUndoWithTarget:(id)target handler:(void (^)(id target))undoHandler API_AVAILABLE(macos(10.11), ios(9.0), watchos(2.0), tvos(9.0)) NS_REFINED_FOR_SWIFT;

//如果撤销组作为一个整体被丢弃，则该密钥具有对应的true值。
FOUNDATION_EXPORT NSString * const NSUndoManagerGroupIsDiscardableKey API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));
// used with NSRunLoop's performSelector:target:argument:order:modes:
static const NSUInteger NSUndoCloseGroupingRunLoopOrdering = 350000;

//可撤销的撤消和重做操作
@property (readonly) BOOL undoActionIsDiscardable API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));
@property (readonly) BOOL redoActionIsDiscardable API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));
- (void)setActionIsDiscardable:(BOOL)discardable API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));

//管理操作名字
@property (readonly, copy) NSString *undoActionName;
@property (readonly, copy) NSString *redoActionName;
- (void)setActionName:(NSString *)actionName;

//获取和本地化菜单项标题
@property (readonly, copy) NSString *undoMenuItemTitle;
@property (readonly, copy) NSString *redoMenuItemTitle;
- (NSString *)undoMenuTitleForUndoActionName:(NSString *)actionName;
- (NSString *)redoMenuTitleForUndoActionName:(NSString *)actionName;

@end
//通知
//打开或关闭撤销组
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerCheckpointNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//将要执行一个撤销操作
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerWillUndoChangeNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//将要执行重做操作
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerWillRedoChangeNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//已经执行一个撤销操作
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerDidUndoChangeNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//已经执行重做操作
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerDidRedoChangeNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));

//已经打开一个撤销组时 beginUndoGrouping
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerDidOpenUndoGroupNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//将要关闭一个撤销组时 endUndoGrouping
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerWillCloseUndoGroupNotification API_AVAILABLE(macos(10.0), ios(3.0), watchos(2.0), tvos(9.0));
//已经关闭一个撤销组时 endUndoGrouping
FOUNDATION_EXPORT NSNotificationName const NSUndoManagerDidCloseUndoGroupNotification API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));

NS_ASSUME_NONNULL_END

参考：https://www.cnblogs.com/xianfeng-zhang/p/9481957.html