////  main.m//  TestVar2////  Created by lishujun on 14-9-4.//  Copyright (c) 2014年 lishujun. All rights reserved.//#import <Foundation/Foundation.h>@interface Address : NSObject<NSCopying>-(void) toString;@end@implementation Address-(void) toString{    NSLog(@"this is an address");}-(id) copyWithZone:(NSZone *)zone{    Address *newAddress = [[Address alloc]init];    return newAddress;}@end@interface Employee : NSObject@property (copy) Address *address; // assign, retain, copy@end@implementation Employee@synthesize address;@endvoid testAssignAndRetain(){    // 创建他们应该都是1    Address *address = [[Address alloc]init];    Address *address2 = [[Address alloc]init];        NSLog(@"a1 = %lu", [address retainCount]);    NSLog(@"a2 = %lu", [address2 retainCount]);        // 首次赋值看看会不会retain    Employee *employee = [[Employee alloc]init];    [employee setAddress: address];    NSLog(@"a1 = %lu", [address retainCount]);    NSLog(@"a2 = %lu", [address2 retainCount]);            // 看看employee.address 和 address还是不是同一个对象    [employee setAddress:address];    NSLog(@"obj address          is %@" , address);    NSLog(@"obj employee.address is %@" , employee.address);        // 再次赋值看看会不会release    [employee setAddress:address2];    NSLog(@"a1 = %lu", [address retainCount]);    NSLog(@"a2 = %lu", [address2 retainCount]);        // 看看使用的时候会不会retain    for (int i=0; i<10; i++) {        [employee.address toString];        NSLog(@"a2 = %lu", [address2 retainCount]);    }}void testCopy1(){    Address *address = [[Address alloc]init];    Address *address2 = [[Address alloc]init];    Employee *employee = [[Employee alloc]init];        // 看看employee.address 和 address还是不是同一个对象    [employee setAddress:address];    NSLog(@"%@" , address);    NSLog(@"%@" , address2);    NSLog(@"%@" , employee.address);        // 看看employee.address 和 address还是不是同一个对象    [employee setAddress:address2];    NSLog(@"%@" , address);    NSLog(@"%@" , address2);    NSLog(@"%@" , employee.address); //之前的对象被替换}void testCopy2(){    Address *address = [[Address alloc]init];    Employee *employee = [[Employee alloc]init];    [employee setAddress:address];        // 看看使用对象会不会retain    for (int i=0; i<10; i++) {        //[employee.address toString];        NSLog(@"address = %lu", [address retainCount]);        NSLog(@"e.address = %lu", [employee.address retainCount]);    }}int main(int argc, const char * argv[]){    @autoreleasepool {        //testAssignAndRetain();        testCopy2();    }    return 0;}