iOS 中CFUUIDRef、 CFUUIDCreate 、CFUUIDCreateString 生成唯一字符串

- (NSString *)pathForTemporaryFileWithPrefix:(NSString *)prefix

{

    NSString *  result;

    CFUUIDRef   uuid;

    CFStringRef uuidStr;

    

    uuid = CFUUIDCreate(NULL);

    assert(uuid != NULL);

    

    uuidStr = CFUUIDCreateString(NULL, uuid);

    assert(uuidStr != NULL);

    

    result = [NSTemporaryDirectory()stringByAppendingPathComponent:[NSStringstringWithFormat:@"%@-%@", prefix, uuidStr]];

    assert(result != nil);

    

    CFRelease(uuidStr);

    CFRelease(uuid);

    

    return result;

}

另一种方法用具体的时间生成文件名

 

[[NSCalendarDate calendarDate] descriptionWithCalendarFormat:@"%m%d%Y%H%M%S%F"]