iOS5中的UUID

在ios5中，UDID已不再被推薦使用，在將來的版本中，這個功能可能會消失。所以我們得探尋它的取代方法，能唯一標識設備的東西。往往硬件上有唯一標識，所以我們可以用硬件上的信息來取代UDID, 硬件上的MAC地址就能達到這樣的目的。

下面的函數就可以返回XX:XX:XX:XX:XX:XX類型的字符串(12個16進制數)

1. #include <sys/socket.h>
2. #include <sys/sysctl.h>
3. #include <net/if.h>
4. #include <net/if_dl.h>
6. ...
8. - (NSString *)getMacAddress
9. {
10. int mgmtInfoBase[6];
11. char *msgBuffer = NULL;
12. size_t length;
13. unsigned char macAddress[6];
14. struct if_msghdr *interfaceMsgStruct;
15. struct sockaddr_dl *socketStruct;
16. NSString *errorFlag = NULL;
18. // Setup the management Information Base (mib)
19. mgmtInfoBase[0] = CTL_NET; // Request network subsystem
20. mgmtInfoBase[1] = AF_ROUTE; // Routing table info
21. mgmtInfoBase[2] = 0;
22. mgmtInfoBase[3] = AF_LINK; // Request link layer information
23. mgmtInfoBase[4] = NET_RT_IFLIST; // Request all configured interfaces
25. // With all configured interfaces requested, get handle index
26. if ((mgmtInfoBase[5] = if_nametoindex("en0")) == 0)
27. errorFlag = @"if_nametoindex failure";
28. else
29. {
30. // Get the size of the data available (store in len)
31. if (sysctl(mgmtInfoBase, 6, NULL, &length, NULL, 0) < 0)
32. errorFlag = @"sysctl mgmtInfoBase failure";
33. else
34. {
35. // Alloc memory based on above call
36. if ((msgBuffer = malloc(length)) == NULL)
37. errorFlag = @"buffer allocation failure";
38. else
39. {
40. // Get system information, store in buffer
41. if (sysctl(mgmtInfoBase, 6, msgBuffer, &length, NULL, 0) < 0)
42. errorFlag = @"sysctl msgBuffer failure";
43. }
44. }
45. }
47. // Befor going any further...
48. if (errorFlag != NULL)
49. {
50. NSLog(@"Error: %@", errorFlag);
51. return errorFlag;
52. }
54. // Map msgbuffer to interface message structure
55. interfaceMsgStruct = (struct if_msghdr *) msgBuffer;
57. // Map to link-level socket structure
58. socketStruct = (struct sockaddr_dl *) (interfaceMsgStruct + 1);
60. // Copy link layer address data in socket structure to an array
61. memcpy(&macAddress, socketStruct->sdl_data + socketStruct->sdl_nlen, 6);
63. // Read from char array into a string object, into traditional Mac address format
64. NSString *macAddressString = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
65. macAddress[0], macAddress[1], macAddress[2],
66. macAddress[3], macAddress[4], macAddress[5]];
67. NSLog(@"Mac Address: %@", macAddressString);
69. // Release the buffer memory
70. free(msgBuffer);
72. return macAddressString;
73. }

系統SKD也提供了一種方法得到標識字符串即UDID，如下：

1. [[UIDevice currentDevice] uniqueIdentifier]

但打開UIDevice.h中你會發現這樣的定義與注釋

1. @property(nonatomic,readonly,retain) NSString *uniqueIdentifier __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_NA,__MAC_NA,__IPHONE_2_0,__IPHONE_5_0); // a string unique to each device based on various hardware info.

UUID在iOS4中也可以用，但不能保證在以後的系統升級後（iOS6 , 7）還能用。ios5中我還沒有測試過，因為現在手裡沒設備了（測了的朋友給我說說結果）。

在此也隨便把得到UUID的方法以寫出來：

1. -(NSString*) uuid
2. {
3. CFUUIDRef puuid = CFUUIDCreate( nil );
4. CFStringRef uuidString = CFUUIDCreateString( nil, puuid );
5. NSString * result = (NSString *)CFStringCreateCopy( NULL, uuidString);
6. CFRelease(puuid);
7. CFRelease(uuidString);
8. return [result autorelease];
9. }

在這兒有兩個概念UUID與UDID.

UUID是Universally Unique Identifier 通用唯一標識碼

UDID是Unique Device Identifier 設備唯一標識碼

UDID只是UUID的一個了集而已。