所谓copy

来源：互联网发布：淘宝买东西返钱的软件编辑：程序博客网时间：2024/06/07 18:41

浅层复制：只复制指向对象的指针，而不复制引用对象本身。

深层复制：复制引用对象本身

copy和mutableCopy的区别在于它们的返回值是其中前者是不可变的类，后者是可变的类.

不管被复制的对象是不可变的还是可变的，copy的返回值类型始终是不可变类型。

#import <Foundation/Foundation.h>int main(int argc, const char * argv[]) {       NSString *str1 = @"hello";    NSString *str2 = [str1 copy];//指针copy    NSString *str3 = [str1 mutableCopy];//深copy    NSLog(@"str1 = %@  str1 = %p",str1,str1);    NSLog(@"str2 = %@  str2 = %p",str2,str2);    NSLog(@"str3 = %@  str3 = %p",str3,str3);     NSMutableString *mutableStr2 = [str1 copy];//指针copy    NSMutableString *mutableStr3 = [str1 mutableCopy];//深copy    NSMutableString *mutableStr4 = [str1 mutableCopy];    [mutableStr4 appendString:@"-OC"];    NSLog(@"mutableStr2 = %@  mutableStr2 = %p",mutableStr2,mutableStr2);    NSLog(@"mutableStr3 = %@  mutableStr3 = %p",mutableStr3,mutableStr3);    NSLog(@"mutableStr4 = %@  mutableStr4 = %p",mutableStr4,mutableStr4);        return 0;}

</pre><pre name="code" class="objc"><pre name="code" class="html">2015-11-06 11:09:03.589 msDemo[1301:43528] str1 = hello  str1 = 0x1000010302015-11-06 11:09:03.590 msDemo[1301:43528] str2 = hello  str2 = 0x1000010302015-11-06 11:09:03.590 msDemo[1301:43528] str3 = hello  str3 = 0x1001145c02015-11-06 11:09:03.590 msDemo[1301:43528] mutableStr2 = hello  mutableStr2 = 0x1000010302015-11-06 11:09:03.590 msDemo[1301:43528] mutableStr3 = hello  mutableStr3 = 0x1001149d02015-11-06 11:09:03.590 msDemo[1301:43528] mutableStr4 = hello-OC  mutableStr4 = 0x1001148d0

</pre><pre name="code" class="objc"><pre name="code" class="objc">2015-11-06 11:14:15.262 msDemo[1309:45570] str1 = hello  str1 = 0x1000010302015-11-06 11:14:15.330 msDemo[1309:45570] str2 = hello  str2 = 0x1000010302015-11-06 11:14:15.331 msDemo[1309:45570] str3 = hello  str3 = 0x100206ba02015-11-06 11:14:15.331 msDemo[1309:45570] mutableStr2 = hello  mutableStr2 = 0x1000010302015-11-06 11:14:15.331 msDemo[1309:45570] mutableStr3 = hello  mutableStr3 = 0x100206eb02015-11-06 11:14:15.331 msDemo[1309:45570] mutableStr4 = hello-OC  mutableStr4 = 0x100207030

</pre><pre name="code" class="objc"><pre name="code" class="objc">2015-11-06 11:14:41.343 msDemo[1313:45789] str1 = hello  str1 = 0x1000010302015-11-06 11:14:41.344 msDemo[1313:45789] str2 = hello  str2 = 0x1000010302015-11-06 11:14:41.344 msDemo[1313:45789] str3 = hello  str3 = 0x100206ba02015-11-06 11:14:41.344 msDemo[1313:45789] mutableStr2 = hello  mutableStr2 = 0x1000010302015-11-06 11:14:41.344 msDemo[1313:45789] mutableStr3 = hello  mutableStr3 = 0x100206cc02015-11-06 11:14:41.344 msDemo[1313:45789] mutableStr4 = hello-OC  mutableStr4 = 0x100206c00

此处特别给出了三次运行结果，可以看出mutableCopy每次复制的地址都不一样，他复制的地址是每次随机复制内存的地址，是深copy，Copy每次运行的结果都相同，都是0x100001030，他只是指针的Copy，不管是NSString还是NSMutableString类型

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