oc51--循环retain

//  main.m
//  循环retain

#import <Foundation/Foundation.h>
#import "Person.h"
#import "Dog.h"

int main(int argc, const char * argv[]) {

    Person *p = [Person new];
    Dog *d = [Dog new];

    // 如果A对用要拥有B对象, 而B对应又要拥有A对象, 此时会形成循环retain
    // 如何解决这个问题: 不要让A retain B, B retain A
    // 让其中一方不要做retain操作即可
    p.dog = d; // retain
    d.owner = p; // retain  assign

    [p release];
    [d release];

    return 0;
}

//  Dog.h

#import <Foundation/Foundation.h>
@class Person;

@interface Dog : NSObject

//@property(nonatomic, retain)Person *owner;
@property(nonatomic, assign)Person *owner;
@end

//  Dog.m

#import "Dog.h"
#import "Person.h"

@implementation Dog

-(void)dealloc
{
    NSLog(@"%s", __func__);
//    [_owner release];
//    self.owner = nil;
    [super dealloc];
}
@end

//
//  Person.h

#import <Foundation/Foundation.h>
@class Dog;

@interface Person : NSObject

@property(nonatomic, retain)Dog *dog;
@end

//  Person.m

#import "Person.h"
#import "Dog.h"

@implementation Person

- (void)dealloc
{
    NSLog(@"%s", __func__);
//    [_dog release];
    self.dog = nil;
    [super dealloc];
}
@end