Posted in Server

VBox, Ubuntu server | Install virtualbox Guest Addition on Ubuntu server

        1. Boot from Ubuntu server
        2. Insert Guest Addition CD
          (Devices menu – Insert Guest Addition CD image…)
        3. Mount Guest Addition CD
          $ sudo mkdir /media/cdrom
          $ sudo mount /dev/cdrom /media/cdrom
          $ cd /media/cdrom
        4. Install packages
          $ sudo apt-get install -y dkms build-essential linux-headers-generic linux-headers-$(uname -r)
        5. Install Guest Addition
        6. $ sudo su
          $ ./
        7. Reboot
Posted in Banana Pi

BPI | Burn the booting image to BPI board

Already did burned the booting image on the board following the post.

And then let’s do burning the booting image on eMMC of the board.

1. .zip image in USB stick

If the booting image needed, download it at the link.
And copy the image to the USB stick.

2. Insert the USB stick to the BPI board

3. Mount the USB on the BPI board

$ sudo mount ‘USB path’ ‘directory’
(Ex. $ sudo mount /dev/sda1 /usb)

4. Burn the image with ‘bpi-copy’ command

$ bpi-copy ‘image path’
(Ex. $ bpi-copy /usb/

Posted in iOS, Swift

iOS, Swift | UI connection between storyboard and .swift source issue


Xcode Version 9.0.1



Error occurs whenever control-drag to connect ui and source from storyboard to .swift file like the screenshot.

Terminating app due to uncaught exception ‘NSUnknownKeyException’, reason: ‘[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key


Try control-drag from an UI image in storyboard to a source code like the above image.

And then build and run an application.

After this, the both ways works.

1st – control-drag from a title of an UI in storyboard to a source file.

2nd – control-drag from an UI image in story board to a source file.

I don’t understand why. But it works for me.