isa class superclass metaclass

 http://www.cnblogs.com/feng9exe/p/7232915.html

Note: 其实这里的难点就在于对 和 的区分。

• .class 当 target 是 Instance 则返回 Class，当 target 是 Class 则返回自身
• object_getClass 返回 指针的指向 

ViewController: 0x10deee650, ViewController, 0

ViewController: 0x10deee678, NSObject, 1

NSObject: 0x10ef8cee8, NSObject, 1

NSObject: 0x10ef8cee8, NSObject, 1

ViewController

UIViewController

UIResponder

NSObject

ViewController: 0x10deee650, ViewController, 0

ViewController: 0x10deee650, ViewController, 0

   Class currentClass = object_getClass(self);

    Class nextClass = object_getClass(currentClass);

    Class superClass = class_getSuperclass(currentClass);

    Class xClass = self.class;

    int k = 0;

    do {

        NSLog(@"%@:\t%p,\t%s,\t%zd",NSStringFromClass(currentClass),currentClass,object_getClassName(currentClass),class_isMetaClass(currentClass));

        currentClass = nextClass;

        nextClass = object_getClass(currentClass);

    }while (k++ < 4);

    

    NSLog(NSStringFromClass(self.class));

    while (superClass != NULL) {

        NSLog(NSStringFromClass(superClass));

        superClass = class_getSuperclass(superClass);

    }

    

    k = 0;

    do {

        NSLog(@"%@:\t%p,\t%s,\t%zd",NSStringFromClass(xClass),xClass,object_getClassName(xClass),class_isMetaClass(xClass));

        xClass = xClass.class;

        //nextClass = object_getClass(currentClass);

    }while (k++ < 3);