@interface Book
{
	int _price;
}


- (void)setPrice:(int)price;
- (int)price;


@end

@implementation Book


- (void)setPrice:(int)price
{


	_price = price;
}


- (int)price
{
	return _price;
}


- (void)dealloc
{
	[_book release];
	_book = nil;


	[super dealloc];
}


@end

@interface Person
{
	Book* _book;
}


- (void)setBook:(Book*)book;
- (Book*)book;


@end

@implementation Person


- (void)setBook:(Book*)book
{
	// retain新的，release旧的，把新的赋给旧的
	if (_book != book){
		[book retain];
		[_book release];
		_book = book;
	}


	/* 可以简写为：
	if (_book != book){
		[_book release];
		_book = [book retain];
	}
	*/
}


- (Book*)book
{
	return _book;
}


@end

#import <Foundation/Foundation.h>


int main()
{
	Person* person = [[Person alloc] init];


	Book* book = [[Book alloc] init];
	[person setBook:book];
	[book release];
	book = nil;


	[person release];


	return 0;
}

iOS复习笔记5:内存管理之set方法