Connect a bluetooth keyboard to Rasperry Pi 3 Arch Linux ARM

I just wanted to connect a bluetooth keyboard WK29B keyboard to my Raspberry Pi. It wasn't immediately straightforward, so I had to:

install base-devel to be able to build packages from AUR
download hciattach-rpi3 and pi-bluetooth
untar both of them (e.g. tar xvf hciattach-rpi3)
build and install hciattach-rpi3 first by makepkg -si
then build and install pi-bluetooth
enable and start bcrm43438 by sudo systemctl enable brcm43438.service, sudo systemctl start brcm43438.service
install bluez, bluez-utils by pacman -Sy bluez
enable and start bluetooth
go to bluetoothctl shell and:

power on  
agent on  
scan on  # make sure that your keyboard/device is discoverable (I had to press ctrl+K)  
trust MAC_ADDRESS  
pair MAC_ADDRESS # I had to "blindly" type some code and press enter  
connect MAC_ADDRESS

That should be all!