objective-c中的深、浅拷贝,objective-c拷贝

objective-c中的深、浅拷贝,objective-c拷贝

浅复制:只复制指向对象的指针,而不复制引用对象本身。计数器+1
,就像比如retain

深层复制:复制引用对象本身。计数器不变,产生新对象 

 

retain:始终是浅复制。引用计数每次加一。返回对象是否可变与被复制的对象保持一致。

 

copy:对于可变对象为深复制,引用计数不改变;对于不可变对象是浅复制,引用计数每次加一。始终返回一个不可变对象。

mutableCopy:始终是深复制,引用计数不改变。始终返回一个可变对象。

 

金沙手机APP 1#import
<Foundation/Foundation.h> int main(int argc, const char *
argv[]) { NSMutableArray *array1=[NSMutableArray
arrayWithObjects:@”two day”, nil]; NSMutableArray *array2=[array1
copy]; NSArray *array3=[array2 copy]; NSArray *array4=[array2
retain]; NSMutableArray *array5=[array1 retain]; NSMutableArray
*array6=[array1 mutableCopy]; NSArray *array7=[array2
mutableCopy]; NSLog(@”————-“); NSLog(@”array1:%@ %p”,array1,
array1); NSLog(@”array2:%@ %p”,array2, array2); NSLog(@”array3:%@
%p”,array3, array3); NSLog(@”array4:%@ %p”,array4, array4);
NSLog(@”array5:%@ %p”,array5, array5); NSLog(@”array6:%@ %p”,array6,
array6); NSLog(@”array7:%@ %p”,array7, array7); NSLog(@”————-“);
return 0; } 源代码

 

金沙手机APP 22015-04-01
20:46:23.131 04-01-person[2204:165655] ————- 2015-04-01
20:46:23.132 04-01-person[2204:165655] array1:( “two day” )
0x100114570 2015-04-01 20:46:23.133 04-01-person[2204:165655] array2:(
“two day” ) 0x100114700 2015-04-01 20:46:23.133
04-01-person[2204:165655] array3:( “two day” ) 0x100114700 2015-04-01
20:46:23.133 04-01-person[2204:165655] array4:( “two day” )
0x100114700 2015-04-01 20:46:23.133 04-01-person[2204:165655] array5:(
“two day” ) 0x100114570 2015-04-01 20:46:23.133
04-01-person[2204:165655] array6:( “two day” ) 0x1001150d0 2015-04-01
20:46:23.134 04-01-person[2204:165655] array7:( “two day” )
0x100115b00 2015-04-01 20:46:23.134 04-01-person[2204:165655]
————- Program ended with exit code: 0 运行结果

 

数组类型转换:

1、不可变对象→可变对象的转换:       

金沙手机APP 3#import
<Foundation/Foundation.h> int main(int argc, const char *
argv[]) { NSArray *array01=[NSArray
arrayWithObjects:@”zhang”,@”wang”,@”li”, nil]; NSMutableArray
*array02=[array01 mutableCopy]; //mutableCopy始终返回一个可变对象
NSLog(@”array01: %@ %p”,array01,array01); NSLog(@”array02: %@
%p”,array02,array02); return 0; } 源代码
金沙手机APP 42015-04-01
21:00:28.218 04-01-person[2252:170414] array01: ( zhang, wang, li )
0x100106c80 2015-04-01 21:00:28.220 04-01-person[2252:170414] array02:
( zhang, wang, li ) 0x1001076d0 Program ended with exit code: 0 运行结果

 

2、可变对象→不可变对象的转换:

金沙手机APP 5#import
<Foundation/Foundation.h> int main(int argc, const char *
argv[]) { NSMutableArray *array1 = [NSMutableArray
arrayWithObjects:@”zhang”,@”wang”,@”li”, nil]; NSArray
*array2=[array1
copy];//copy对于可变对象为深复制,引用计数不改变;对于不可变对象是浅复制,引用计数每次加一。始终返回一个不可变对象
NSLog(@”array1: %@ %p”,array1,array1); NSLog(@”array2: %@
%p”,array2,array2); return 0; } 源代码
金沙手机APP 62015-04-01
21:03:45.349 04-01-person[2263:171615] array1: ( zhang, wang, li )
0x100112900 2015-04-01 21:03:45.350 04-01-person[2263:171615] array2:
( zhang, wang, li ) 0x1001133b0 运行结果

 

3、可变对象→可变对象的转换(不同指针变量指向不同的内存地址):

金沙手机APP 7#import
<Foundation/Foundation.h> int main(int argc, const char *
argv[]) { NSMutableArray *array1= [金沙手机APP,NSMutableArray
arrayWithObjects:@”zhang”,@”wang”,@”li”, nil]; NSMutableArray
*array2=[array1 mutableCopy]; NSLog(@”array1: %@ %p”,array1,array1);
NSLog(@”array2: %@ %p”,array2,array2); return 0; } 源代码
金沙手机APP 82015-04-01
20:57:41.732 04-01-person[2243:169571] array1: ( zhang, wang, li )
0x100114570 2015-04-01 20:57:41.734 04-01-person[2243:169571] array2:
( zhang, wang, li ) 0x100115020 Program ended with exit code: 0 运行结果

 

 

4、同类型对象之间的指针复制(不同指针变量指向同一块内存地址):

金沙手机APP 9#import
<Foundation/Foundation.h> int main(int argc, const char *
argv[]) { NSArray *array1=[NSArray
arrayWithObjects:@”one”,@”two”,@”three”, nil]; NSArray
*array2=[array1 copy]; NSLog(@”array1: %@ %p”,array1,array1);
NSLog(@”array2: %@ %p”,array2,array2); return 0; } 源代码
金沙手机APP 102015-04-01
20:53:07.398 04-01-person[2217:167996] array1: ( one, two, three )
0x1006069a0 2015-04-01 20:53:07.399 04-01-person[2217:167996] array2:
( one, two, three ) 0x1006069a0 Program ended with exit code: 0 运行结果

当多个指针同时指向同一块内存区域,那么这些个指针同时拥有对该内存区的所有权。所有权的瓜分过程,这时候就要用到浅拷贝了。

 

 

 

 

 

 

浅复制: 只复制指向对象的指针,而不复制引用对象本身。计数器+1
,就像比如retain 深层复制:复…

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