iOS 生成 UUID(GUID)

iOS 生成 UUID（或者叫GUID）例子代码

NSString * gen_uuid()

{

CFUUIDRef uuid_ref = CFUUIDCreate(NULL);

CFStringRef uuid_string_ref= CFUUIDCreateString(NULL, uuid_ref);

CFRelease(uuid_ref);

NSString *uuid = [NSString stringWithString:(NSString*)uuid_string_ref];

CFRelease(uuid_string_ref);

return uuid;

}

在oc中，uuid的表示

1,用一个16个字节的数组表示

 ／／guid

typedef struct {

#define KAUTH_GUID_SIZE 16/* 128-bit identifier */

unsignedchar g_guid[KAUTH_GUID_SIZE];

} guid_t;

／／uuid

typedef unsigned char __darwin_uuid_t[16];//定义了一个元素类型为unsigned char，含有16个元素的数组类型__darwin_uuid_t,以后使用__darwin_uuid_t定义的类型都是一个含有16个字符的数组

typedef __darwin_uuid_t uuid_t;

2,使用结构体表示

typedef struct {
   UInt8 byte0;
   UInt8 byte1;
   UInt8 byte2;
   UInt8 byte3;
   UInt8 byte4;
   UInt8 byte5;
   UInt8 byte6;
   UInt8 byte7;
   UInt8 byte8;
   UInt8 byte9;
   UInt8 byte10;
   UInt8 byte11;
   UInt8 byte12;
   UInt8 byte13;
   UInt8 byte14;
   UInt8 byte15;
} CFUUIDBytes;

3,在 iOS6.0之后，可以使用系统自带的NSUUID类