NSObject学习

1. - (id)copy //Returns the object returned by copyWithZone:.调用copyWithZone方法实现复制功能，若是自己的类

           //则需要实现copyWithZone方法

1. 如：NSString *str2 = [str1 copy];
2.  + (id)copyWithZone:(struct _NSZone *)zone//copy方法的实现者
   1. -(id)copyWithZone:(NSZone *)zone

{

Engine * engineCopy;

copyWithZone = [[[self class]allocWithZone:zone]init];

Return(engineCopy)

}   

3. - (id)mutableCopy//同copy,这里获得的是可变的对象
   1. 如：NSMutableString  * mutableStr1= [str1 mutableCopy];
4. + (id)mutableCopyWithZone:(struct _NSZone *)zone//不关注
5. + (Class)class//Returns the class object. 返回类对象
   1. BOOLtest= [selfisKindOfClass:[SomeClassclass]];
6. + (Class)superclass//Returns the class object for the receiver’s superclass.返回父类的类对象
7. +(BOOL)isSubclassOfClass:(Class)aClass//判断消息接收者所属的类是不是aClass的子类
8. + (BOOL)instancesRespondToSelector:(SEL)aSelector//判断对象能否相应给定的选择器（方法）
9. + (BOOL)conformsToProtocol:(Protocol *)aProtocol//判断对象是否实现给定的协议
10. ……
11. + (NSString *)description//描述
12. - (void)performSelector:(SEL)aSelectorwithObject:(id)anArgumentafterDelay:(NSTimeInterval)delay
    1. Invokes a method of the receiver on the current thread using the default mode after a delay.
13. - (BOOL)isKindOfClass:(Class)aClass
    1. Returns a Boolean value that indicates whether the receiver is an instance of given class or an instance of any class that inherits from that class. (required)
14. - (BOOL)isMemberOfClass:(Class)aClass
    1. Returns a Boolean value that indicates whether the receiver is an instance of a given class. (required)
    2. 是不是给定类的子类
15. - (BOOL)respondsToSelector:(SEL)aSelector
    1. Returns a Boolean value that indicates whether the receiver implements or inherits a method that can respond to a specified message. (required)
16. - (BOOL)conformsToProtocol:(Protocol *)aProtocol
    1. Returns a Boolean value that indicates whether the receiver conforms to a given protocol. (required)
17. - (id)performSelector:(SEL)aSelector
    1. Sends a specified message to the receiver and returns the result of the message. (required)
18. - (id)performSelector:(SEL)aSelectorwithObject:(id)anObject//同上，object是传入的参数可为nil
19. ……