NSObject

Objective-C是动态语言，每个类class都会在运行时创建一个类对象。

NSObject是根类，当然是最重要的一个类，提供的一些公共方法，顾名思议。

@protocol NSObject
// 是否引用同一对象
- (BOOL)isEqual:(id)object;
- (NSUInteger)hash;


- (Class)superclass;
- (Class)class;
- (id)self;
- (NSZone *)zone NS_AUTOMATED_REFCOUNT_UNAVAILABLE;

- (id)performSelector:(SEL)aSelector;
- (id)performSelector:(SEL)aSelector withObject:(id)object;
- (id)performSelector:(SEL)aSelector withObject:(id)object1 withObject:(id)object2;

- (BOOL)isProxy;

- (BOOL)isKindOfClass:(Class)aClass;
- (BOOL)isMemberOfClass:(Class)aClass;
- (BOOL)conformsToProtocol:(Protocol *)aProtocol;

- (BOOL)respondsToSelector:(SEL)aSelector;

- (id)retain NS_AUTOMATED_REFCOUNT_UNAVAILABLE;
- (oneway void)release NS_AUTOMATED_REFCOUNT_UNAVAILABLE;
- (id)autorelease NS_AUTOMATED_REFCOUNT_UNAVAILABLE;
- (NSUInteger)retainCount NS_AUTOMATED_REFCOUNT_UNAVAILABLE;

- (NSString *)description;
@optional
- (NSString *)debugDescription;

@end
// 浅copy
@protocol NSCopying

- (id)copyWithZone:(NSZone *)zone;

@end
// 深copy
@protocol NSMutableCopying

- (id)mutableCopyWithZone:(NSZone *)zone;

@end
// 序列化
@protocol NSCoding

- (void)encodeWithCoder:(NSCoder *)aCoder;
- (id)initWithCoder:(NSCoder *)aDecoder;

@end

// Objects which are safe to be encoded and decoded across privilege boundaries should adopt NSSecureCoding instead of NSCoding. Secure coders (those that respond YES to requiresSecureCoding) will only encode objects that adopt the NSSecureCoding protocol.
@protocol NSSecureCoding <NSCoding>
@required
// This method must be return YES on all classes that allow secure coding. Subclasses of classes that adopt NSSecureCoding and override initWithCoder: must also override this method and return YES.
// The Secure Coding Guide should be consulted when writing methods that decode data.
+ (BOOL)supportsSecureCoding;
@end

/***********    Base class        ***********/

NS_ROOT_CLASS
@interface NSObject <NSObject> {
    Class    isa;
}

+ (void)load;

+ (void)initialize;
- (id)init;

+ (id)new;
+ (id)allocWithZone:(NSZone *)zone;
+ (id)alloc;
- (void)dealloc;

- (void)finalize;

- (id)copy;
- (id)mutableCopy;

+ (id)copyWithZone:(NSZone *)zone NS_AUTOMATED_REFCOUNT_UNAVAILABLE;
+ (id)mutableCopyWithZone:(NSZone *)zone NS_AUTOMATED_REFCOUNT_UNAVAILABLE;

+ (Class)superclass;
+ (Class)class;
+ (BOOL)instancesRespondToSelector:(SEL)aSelector;
+ (BOOL)conformsToProtocol:(Protocol *)protocol;
- (IMP)methodForSelector:(SEL)aSelector;
+ (IMP)instanceMethodForSelector:(SEL)aSelector;
- (void)doesNotRecognizeSelector:(SEL)aSelector;

- (id)forwardingTargetForSelector:(SEL)aSelector NS_AVAILABLE(10_5, 2_0);
- (void)forwardInvocation:(NSInvocation *)anInvocation;
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector;

+ (NSMethodSignature *)instanceMethodSignatureForSelector:(SEL)aSelector;

- (BOOL)allowsWeakReference NS_UNAVAILABLE;
- (BOOL)retainWeakReference NS_UNAVAILABLE;

+ (NSString *)description;

+ (BOOL)isSubclassOfClass:(Class)aClass;

+ (BOOL)resolveClassMethod:(SEL)sel NS_AVAILABLE(10_5, 2_0);
+ (BOOL)resolveInstanceMethod:(SEL)sel NS_AVAILABLE(10_5, 2_0);

@end

@interface NSObject (NSCoderMethods)

+ (NSInteger)version;
+ (void)setVersion:(NSInteger)aVersion;
- (Class)classForCoder;
- (id)replacementObjectForCoder:(NSCoder *)aCoder;
- (id)awakeAfterUsingCoder:(NSCoder *)aDecoder NS_REPLACES_RECEIVER;

@end