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renjinkui2719 / DIS_KVC_KVO

  • пятница, 2 июня 2017 г. в 03:12:10
https://github.com/renjinkui2719/DIS_KVC_KVO

Objective-C
DIS_KVC_KVO



DIS_KVC_KVO

根据IOS Foundation框架汇编反写的KVC,KVO实现，可以在mac, IOS环境下运行调试, KVC与KVO实现机制密不可分，所以将它们作为一个工程。

主要用作学习与研究，加深对KVC,KVO机制的理解，理解oc runtime在这些机制实现中的重要作用.

为了在xcode里正确编译调试,工程代码命名遵循一个规则:
和系统冲突的地方全部用D或者d_前缀修饰. 比如:

Category NSObject+NSKeyValueCoding, 在工程实现中改名为NSObject+DSKeyValueCoding
同理:
方法 - (id)valueForKey:(NSString *)key ==> - (id)d_valueForKey:(NSString *)key

方法 - (void)addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context ==> - (void)d_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context

...

类NSKeyValueObservance ==> DSKeyValueObservance

类NSKeyValueChangeDictionary ==> DSKeyValueChangeDictionary

...

//////////////补充说明 2017-06-01 18:10//////////////
有位兄弟说我的这份代码是盗用Apportable的，为了证明清白，也针对对他的质疑做如下说明:

(0).我今天才知道Apportable这份开源代码,我不确定能不能跑得起来测试

(1).借助IDA，Hopper等反汇编工具，任何人都可以从OC二进制文件中清晰看出类的继承体系，方法列表(不带参数命名)，Protocol列表，ivar和property列表

(2).逆向编程的一个基本过程就是翻译,汇编怎么写，就怎么翻译，变量命名不一样，编程风格不同，但是逻辑一定相同

(3).假设有个selector叫"-(void)setName:age:sex",很容易推出带参数的版本:"-(void)setName:(NSString *)name age:(int)age sex:(int)sex"  

真正体现难度的是c函数，结构体及结构体成员，指针含义的推测。

以我的实现和Apportable实现做几点对比:

举几个结构体的例子

Apportable对几个重要结构体的定义:

typedef struct {
    id _field1;
    NSMutableDictionary *recursedMutableDictionary;
} NSKeyValueForwardingValues;

typedef struct {
    NSKeyValueChange _changeKind;
    NSIndexSet *_indexes;
} NSKeyValueChangeByOrderedToManyMutation;

typedef struct {
    NSKeyValueSetMutationKind _mutationKind;
    NSSet *_objects;
} NSKeyValueChangeBySetMutation;

typedef struct {
    Class _originalClass;
    Class _notifyingClass;
    CFMutableSetRef _field3;
    CFMutableDictionaryRef _cachedKeys;
} NSKVONotifyingInfo;

typedef struct {
    Class alwaysNilFakeIsa;
    NSKeyValueContainerClass *containerClass;
    NSString *keyPath;
} NSKVOFakeProperty;

typedef struct {
    NSObject *originalObservable;
    NSKeyValueObservance *observance;
} NSKeyValueImplicitObservanceAdditionInfo;

typedef struct {
    NSObject *nextObject;
    NSKeyValueObservance *observingObservance;
    NSString *keyPath;
    NSObject *originalObservable;
    NSKeyValueProperty *property;
    BOOL isRecursing; //?
} NSKeyValueImplicitObservanceRemovalInfo;

typedef struct {
    CFMutableArrayRef pendingNotifications;
    BOOL nextIsObservationInfo;
    union {
        NSKeyValueImplicitObservanceAdditionInfo implicitObservanceAdditionInfo;
        NSKeyValueObservationInfo *observationInfo;
    } implicitObservanceAdditionInfoOrObservationInfo;
    NSKeyValueImplicitObservanceRemovalInfo implicitObservanceRemovalInfo;
    NSInteger recursionLevel;
} NSKeyValueObservingTSD;

typedef struct {
    short retainCount;
    BOOL reserved;
    NSObject *originalObservable;
    NSObject *observer;
    id keyOrKeys;
    NSKeyValueObservationInfo *observationInfo;
    NSKeyValueObservance *observance;
    NSKeyValueChangeDetails changeDetails;
    NSKeyValueForwardingValues forwardingValues;
    NSInteger recursionLevel;
} NSKVOPendingNotificationInfo;

typedef struct {
    CFMutableArrayRef pendingNotifications;
    NSInteger pendingNotificationCount;
    NSKVOPendingNotificationInfo *relevantNotification;
    NSInteger relevantNotificationIndex;
    NSKeyValueObservance *observance;
    NSInteger recursionLevel;
} NSKVOPopNotificationResult;

我的定义

typedef struct {
    //引用计数
    uint16_t retainCount;
    //是否是一次change的起始
    BOOL beginningOfChange;
    
    id object;//4
    id keyOrKeys;//8
    DSKeyValueObservationInfo *observationInfo;//c
    DSKeyValueObservance *observance;//10
    NSKeyValueChange kind;//14
    id oldValue;//18
    id newValue;//1c
    NSIndexSet *indexes;//20
    NSMutableData * extraData;//24
    id changingValue;//28
    NSMutableDictionary *affectingValuesMap;//2c
}DSKVOPendingChangeNotificationPerThread;

typedef struct {
    CFMutableArrayRef pendingArray;//0
    BOOL beginningOfChange;//4
    DSKeyValueObservationInfo *observationInfo;//8
}DSKVOPushInfoPerThread;

typedef struct {
    CFMutableArrayRef pendingArray;//0
    NSUInteger pendingCount;//4
    DSKVOPendingChangeNotificationPerThread * lastPopedNotification;//8
    NSInteger lastPopdIndex;//c
    DSKeyValueObservance * observance;//10
}DSKVOPopInfoPerThread;

typedef union {
    struct {
        NSKeyValueChange changeKind;
        NSIndexSet *indexes;
    };
    struct {
        NSKeyValueSetMutationKind mutationKind;
        NSSet *objects;
    };
}DSKVOCollectionWillChangeInfo;

typedef struct {
    DSKeyValueObservance *observance;
    NSKeyValueChange kind;
    id oldValue;
    id newValue;
    NSIndexSet *indexes;
    NSMutableData * extraData;
    id changingValue;
    NSMutableDictionary * affectingValuesMap;
    //??以下字段无法推断命名及含义，并且在KVO中无作用
    BOOL unknow_1;
    NSString *keyOrKeys;
}DSKVOPendingChangeNotificationLocal;

typedef struct {
    NSUInteger capacity;
    BOOL notificationsInStack;
    DSKVOPendingChangeNotificationLocal *notifications;
    NSUInteger notificationCount;
     //??以下字段无法推断命名及含义，并且在KVO中无作用
    BOOL unknow_1;
    id unknow_2;
}DSKVOPushInfoLocal;

typedef struct {
    DSKVOPendingChangeNotificationLocal *notifications;
    NSUInteger notificationCount;
    id observer;
    id oldValue;
    id lastChangingValue;
    DSKeyValueObservationInfo *observationInfo;
}DSKVOPopInfoLocal;

两种实现都有些字段含义无法推断出，其次大部分结构体结构(含义，内存布局)完全不相同

再举个细节例子

在自动通知模式下,如果被监听对象自己覆写了willChangeValueForKey:或者didChangeValueForKey:方法，整个通知路径走的就会是另一条，这个特征apportable没有实现,有兴趣的朋友可以打个断点测试一下

最后举一个Apportable没有解决的BUG，我帮他找出了没能解决的原因

image