深浅复制

什么是深、浅复制

浅复制：只是指针指向所复制的对象，共用一段内存
深复制：完全拷贝一份对象，不共用内存

iOS中深、浅复制总结

	copy	mutableCopy
不可变对象（NSString、NSArray）	浅拷贝	深拷贝
可变对象（NSMutableString、NSMutableArray）	深拷贝	深拷贝

NSString测试

    NSString *str1 = [NSString stringWithFormat:@"abc"];
    NSString *str2 = str1.copy;
    NSString *str3 = str1.mutableCopy;
    NSLog(@"str1 = %p",str1);
    NSLog(@"str2 = %p",str2);
    NSLog(@"str3 = %p",str3);
//    2016-06-30 15:41:32.314 测试深复制，浅复制[1475:450106] str1 = 0xa000000006362613
//    2016-06-30 15:41:32.315 测试深复制，浅复制[1475:450106] str2 = 0xa000000006362613
//    2016-06-30 15:41:32.315 测试深复制，浅复制[1475:450106] str3 = 0x144624f40

NSMutableString测试

    NSMutableString *str1 = [NSMutableString stringWithFormat:@"abc"];
    NSMutableString *str2 = str1.copy;
    NSMutableString *str3 = str1.mutableCopy;
    NSLog(@"str1 = %p-%@",str1,str1);
    NSLog(@"str2 = %p-%@",str2,str2);
    NSLog(@"str3 = %p-%@",str3,str3);
//    2016-06-30 15:47:16.537 测试深复制，浅复制[1489:452181] str1 = 0x12552e7a0-abc
//    2016-06-30 15:47:16.537 测试深复制，浅复制[1489:452181] str2 = 0xa000000006362613-abc
//    2016-06-30 15:47:16.537 测试深复制，浅复制[1489:452181] str3 = 0x1255340b0-abc

NSArray测试

    NSArray *arr1 = [NSArray arrayWithObjects:@"a",@"b", nil];
    NSArray *arr2 =arr1.copy;
    NSArray *arr3 =arr1.mutableCopy;
    NSLog(@"arr1=%p",arr1);
    NSLog(@"arr2=%p",arr2);
    NSLog(@"arr3=%p",arr3);
//    2016-06-30 15:49:32.252 测试深复制，浅复制[1493:452752] arr1=0x125547bd0
//    2016-06-30 15:49:32.253 测试深复制，浅复制[1493:452752] arr2=0x125547bd0
//    2016-06-30 15:49:32.253 测试深复制，浅复制[1493:452752] arr3=0x125541420

NSMutableArray测试

    NSMutableArray *arr1 = [NSMutableArray arrayWithObjects:@"a",@"b", nil];
    NSMutableArray *arr2 =arr1.copy;
    NSMutableArray *arr3 =arr1.mutableCopy;
    NSLog(@"arr1=%p",arr1);
    NSLog(@"arr2=%p",arr2);
    NSLog(@"arr3=%p",arr3);
//    2016-06-30 15:52:23.191 测试深复制，浅复制[1500:453692] arr1=0x147d22960
//    2016-06-30 15:52:23.191 测试深复制，浅复制[1500:453692] arr2=0x147d05ff0
//    2016-06-30 15:52:23.191 测试深复制，浅复制[1500:453692] arr3=0x147d10c40

NSDictionary测试

    NSDictionary *dict1 = [NSDictionary new];
    NSDictionary *dict2 = dict1.copy;
    NSDictionary *dict3 = dict1.mutableCopy;
    NSLog(@"dict1=%p",dict1);
    NSLog(@"dict2=%p",dict2);
    NSLog(@"dict3=%p",dict3);
//    2016-06-30 15:55:03.152 测试深复制，浅复制[1504:454390] dict1=0x135d003f0
//    2016-06-30 15:55:03.153 测试深复制，浅复制[1504:454390] dict2=0x135d003f0
//    2016-06-30 15:55:03.153 测试深复制，浅复制[1504:454390] dict3=0x135d32690

NSMutableDictionary测试

    NSMutableDictionary *dict1 = [NSMutableDictionary new];
    NSMutableDictionary *dict2 = dict1.copy;
    NSMutableDictionary *dict3 = dict1.mutableCopy;
    NSLog(@"dict1=%p",dict1);
    NSLog(@"dict2=%p",dict2);
    NSLog(@"dict3=%p",dict3);
//    2016-06-30 15:55:44.300 测试深复制，浅复制[1507:454706] dict1=0x13c51cda0
//    2016-06-30 15:55:44.300 测试深复制，浅复制[1507:454706] dict2=0x13c603c90
//    2016-06-30 15:55:44.300 测试深复制，浅复制[1507:454706] dict3=0x13c55d8b0

测试数组内部元素在拷贝过程中是否发生改变

    NSMutableString *str1 = [NSMutableString stringWithFormat:@"str1"];
    NSLog(@"str1 地址=%p",str1);
  
    NSMutableString *str2 = [NSMutableString stringWithFormat:@"str2"];
    NSLog(@"str2 地址=%p",str2);
    NSMutableArray *mArr=[NSMutableArray arrayWithObjects:str1,str2, nil];
    NSLog(@"mArr 地址=%p",mArr);
    [[mArr objectAtIndex:0] appendString:@"append111"];
    NSLog(@":append111:%@",str1);
    NSLog(@"mArr[0] 地址=%p",[mArr objectAtIndex:0]);
    
    NSArray *copyArr = mArr.copy;
    [[mArr objectAtIndex:0] appendString:@"append222"];
    NSLog(@"append222:%@",str1);
    NSLog(@"copyArr 地址=%p",copyArr);
    
    NSLog(@"copyArr[0] 地址=%p",[copyArr objectAtIndex:0]);
    /*
    测试容器类数据指针问题[2987:2525070] str1 地址=0x608000264a80
    测试容器类数据指针问题[2987:2525070] str2 地址=0x60000026b280
    测试容器类数据指针问题[2987:2525070] mArr 地址=0x608000053e60
   测试容器类数据指针问题[2987:2525070] :append111:str1append111
    测试容器类数据指针问题[2987:2525070] mArr[0] 地址=0x608000264a80
    测试容器类数据指针问题[2987:2525070] append222:str1append111append222
    测试容器类数据指针问题[2987:2525070] copyArr 地址=0x60800003fa80
    测试容器类数据指针问题[2987:2525070] copyArr[0] 地址=0x608000264a80
*/

说明数组在copy过程中内容的指针还是指向了同一个地址