An easy way to import a file from another device is to transfer the file to you iOS device as an email attachment. Go to Mail then tap and hold the file icon or use the “Open in…” feature and select “GraphicalGW”.

You can also use certain third-party apps to open a Logger Pro file in Graphical Analysis GW. Dropbox and Google Drive are good examples; tap the action/share button and choose “Open in…”

Note: Some third-party mail apps, such as Gmail and Yahoo Mail, may not support the “Open in…” feature. See:
When I tap on an email attachment to open it in Graphical Analysis GW for iOS, it doesn't work.

Related:
Can I open data files, such as Logger Pro or LabQuest files, in Graphical Analysis GW for iOS devices?
I imported a file into Graphical Analysis GW for iOS, but I can't see the calculated columns. What is wrong?
How do I export data from Video Physics to Logger Pro?