oc内存回收问题，求解

#import <Foundation/Foundation.h>
 
@interface Person : NSObject
 
@end

#import "Person.h"
 
@implementation Person
 
- (void)dealloc
{
    NSLog(@"Person dealloc:%p",self);
}
 
@end

#import <Foundation/Foundation.h>
#import "Person.h"
 
Person * test1();
 
int main(int argc, const char * argv[]) {
    Person *p1 = test1();
    NSLog(@"p1:%p",p1);
    p1 = nil;
 
    Person *p2 =test1();
    NSLog(@"p2:%p",p2);
    p2 = nil;
 
    Person *p3 =test1();
    NSLog(@"p3:%p",p3);
    p3 = nil;
 
    return 0;
}
 
Person * test1()
{
    Person *p1 = [Person new];
    return p1;
}