Memory management of memory management 2-set Method-Program parsing

Create a class book

. h has @ property, float price; @synthesize Automatic

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Create a class Student

#import "Book.h"

. h has @property int age;

@property book *book; @synthesize Automatic

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Verifying that the Student object is recycled

Student.m

-(void) dealloc{

NSLog (@ "Student:%i was destroyed", _age);

[Super Dealloc];

}

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To facilitate access to _age create a construction method that can pass in _age

Student.h

-(ID) initwithage: (int) age;

Student.m

-(ID) initwithage: (int) age{

if (Self=[super init]) {//If Super returns an object that is not empty

_age=age;

}

return self;

}

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Verifying that the book object is recycled

Book.m

-(void) dealloc{

NSLog (@ "Book:%f was destroyed", _price);

[Super Dealloc];

}

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With _price book constructor

Book.h

-(void) Initwithprice: (float) Price;

Book.m

-(void) Initwithprice: (float) price{

if (Self=[super init]) {//If Super returns an object that is not empty

_price=price;

}

}

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Annotation method

1 #pragma Mark Constructor

(advantage:easy:locate)

2 #pragma mark -groupname

(Advantage:group)

3 of course//can work

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Main.m

#import "Book.h"

#import "Student.h"

Main () {

@autoreleasepool {

Student *stu=[[student Alloc]initwithage:10]; Stu 1

Book *book =[[book alloc]initwithprice:3.5];//Book 1

stu.book=book;//in reality never with this Way//book 1

[Book Release];//book 0

[Stu Release];//stu 0

}

return 0;

}

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Student.m

Manually realize Getter & Setter

Standard realization of Getter and setter

Student.h//Because u do manually so XCode won't call @synthesize, so there are no//_book,so we need to state _book Ourself.

@interface student:nsobject{

Book *_book;

}

Student.m

-(void) Setbook: (book *) book{

_book=book;

}

-(book *) book{

return _book;

}

Abopve Six line can is short for

@synthesize Book=_book;

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Then counter

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When we developing in reality, we could use object

So change code

Main.m

void Test (Student *stu) {

Book *book=[[book alloc]initwithprice:3.5];

Stu.book=book;

[Book release];

}

void Test1 (Student *stu) {

Add Reading method

Student.h-(void) Readbook;

Student.m

-(void) readbook{

NSLog (@ "Reading book is:%f", _book.price);

//}

[Stu readbook];//not safe, visiting _book,because in test book was released so (wild pointer)

}

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Change code

Main () {

Test (STU);

Test1 (Stu);

}

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Student want to make use of the book object So, retain book in student

Setbook Retain;stu alloc Release

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Improve Code

So compare the passed book object with a current book object if not the same one,

Release the previous one.

-(void) Setbook: (book *) book{

if (Self.book!=book) {

[_book release]; Empty pointer is safe.

_book=[book retain];

}

}

Be released (-1) and destroyed (0) different

Memory management of memory management 2-set Method-Program parsing