iOS复习笔记5:内存管理之set方法

1 alloc和release成对出现

2 set方法

2.1 基础类型直接赋值

2.2 OC对象：判断不等、retain新的，释放旧的，再赋值

3 dealloc方法

3.1 一定要调用[super dealloc];且放在最后

3.2 self拥有的对象要做一次release

@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;
}