ios生成guid代码

1.  + (NSString*) stringWithUUID {

2.     CFUUIDRef    uuidObj = CFUUIDCreate(nil);//create a new UUID
3.     //get the string representation of the UUID
4.     NSString    *uuidString = (NSString*)CFUUIDCreateString(nil, uuidObj);
5.     CFRelease(uuidObj);
6.     return [uuidString autorelease];
7.  }