ARC下的内存管理

int main(int argc, const char * argv[]) {
   @autoreleasepool {
        Person *p = [[Person alloc] init];
    } // 执行到这一行局部变量p释放
    // 由于没有强指针指向对象, 所以对象也释放
    return 0;
}

int main(int argc, const char * argv[]) {
   @autoreleasepool {
        Person *p = [[Person alloc] init];
        p = nil; // 执行到这一行, 由于没有强指针指向对象, 所以对象被释放
    }
    return 0;
}

int main(int argc, const char * argv[]) {
   @autoreleasepool {
        // p是弱指针, 对象会被立即释放
        __weak Person *p1 = [[Person alloc] init];
    }
    return 0;
}

@interface Person : NSObject

// MRC写法
//@property (nonatomic, retain) Dog *dog;

// ARC写法
@property (nonatomic, strong) Dog *dog;

@end

@interface Person : NSObject

//@property (nonatomic, retain) Dog *dog;
@property (nonatomic, strong) Dog *dog;

@end

@interface Dog : NSObject

// 错误写法, 循环引用会导致内存泄露
//@property (nonatomic, strong) Person *owner;

// 正确写法, 当如果保存对象建议使用weak
//@property (nonatomic, assign) Person *owner;
@property (nonatomic, weak) Person *owner;
@end