The following steps are showing how I did setup my wireless connection with an static IP on my ArchLinux driven RaspberryPi. You need to have installed sudo to uses this instructions:

1. Update all packages:

   $> sudo pacman -Syu

2. Install dialog package:

   $> sudo pacman -S dialog

3. Install wpa_supplicant package

   $> sudo pacman -S wpa_supplicant

4. Run wifi-menu:

   $> sudo wifi-menu -o

   This will start the Wifi-Setup dialog.

5. Select your network:
   
6. Choose a name for the profile:
   
7. Insert Wifi password:
   
8. The dialog will close automatically.
9. Edit the generated config file (/etc/netctl/YOUR-ENTERED-PROFILE-NAME):

   $> sudo nano /etc/netctl/wlan0-Valhalla

10. Set IP-type static, IP-Address, Gateway and DNS server like this:

    Description='Valhalla at home'
    Interface=wlan0
    Connection=wireless
    Security=wpa
    ESSID=Valhalla
    IP=static
    Key=\"aaddggeeejjenneggtssskkkekddwsdsaduawvwddvgvdgvasdg
    Address=('192.168.1.4/24')
    Gateway=('192.168.1.4')
    DNS=('192.168.1.1')
    

    The relevant lines are:
    – IP=static
    – Address=(‘192.168.1.4/24’)
    – Gateway=(‘192.168.1.4’)
    – DNS=(‘192.168.1.1’)

11. Now you can enable the profile, so that your pi starts with it:

    $> sudo netctl enable wlan0-Valhalla
    $> sudo netctl start wlan0-Valhalla

12. Reboot the system:

    $> sudo reboot

The blogpost Setup an static IP on Arch Linux shows how to setup a static IP for ethernet connections.