iOS 之动态运行时 runtime <二>

/* Working with Classes */

/** 
 * Returns the name of a class.
 * 
 * @param cls A class object.
 * 
 * @return The name of the class, or the empty string if \e cls is \c Nil.
 */
OBJC_EXPORT const char *class_getName(Class cls) 
     __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

/** 
 * Returns a Boolean value that indicates whether a class object is a metaclass.
 * 
 * @param cls A class object.
 * 
 * @return \c YES if \e cls is a metaclass, \c NO if \e cls is a non-meta class, 
 *  \c NO if \e cls is \c Nil.
 */
OBJC_EXPORT BOOL class_isMetaClass(Class cls) 
     __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

/** 
 * Returns the superclass of a class.
 * 
 * @param cls A class object.
 * 
 * @return The superclass of the class, or \c Nil if
 *  \e cls is a root class, or \c Nil if \e cls is \c Nil.
 *
 * @note You should usually use \c NSObject‘s \c superclass method instead of this function.
 */
OBJC_EXPORT Class class_getSuperclass(Class cls) 
     __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

/** 
 * Sets the superclass of a given class.
 * 
 * @param cls The class whose superclass you want to set.
 * @param newSuper The new superclass for cls.
 * 
 * @return The old superclass for cls.
 * 
 * @warning You should not use this function.
 */
OBJC_EXPORT Class class_setSuperclass(Class cls, Class newSuper) 
     __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_5,__MAC_10_5, __IPHONE_2_0,__IPHONE_2_0);

/** 
 * Returns the version number of a class definition.
 * 
 * @param cls A pointer to a \c Class data structure. Pass
 *  the class definition for which you wish to obtain the version.
 * 
 * @return An integer indicating the version number of the class definition.
 *
 * @see class_setVersion
 */
OBJC_EXPORT int class_getVersion(Class cls)
    __OSX_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** 
 * Sets the version number of a class definition.
 * 
 * @param cls A pointer to an Class data structure. 
 *  Pass the class definition for which you wish to set the version.
 * @param version An integer. Pass the new version number of the class definition.
 *
 * @note You can use the version number of the class definition to provide versioning of the
 *  interface that your class represents to other classes. This is especially useful for object
 *  serialization (that is, archiving of the object in a flattened form), where it is important to
 *  recognize changes to the layout of the instance variables in different class-definition versions.
 * @note Classes derived from the Foundation framework \c NSObject class can set the class-definition
 *  version number using the \c setVersion: class method, which is implemented using the \c class_setVersion function.
 */
OBJC_EXPORT void class_setVersion(Class cls, int version)
    __OSX_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);

/** 
 * Returns the size of instances of a class.
 * 
 * @param cls A class object.
 * 
 * @return The size in bytes of instances of the class \e cls, or \c 0 if \e cls is \c Nil.
 */
OBJC_EXPORT size_t class_getInstanceSize(Class cls) 
     __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);