Because I use tabs, I was eager for a solution that wouldn't open a document from the first tab. I ended up with following:
Note: If Assistant editor is opened, the file from the Standard Editor (on the left side) is opened regardless which editor is active, but for me it's better than the first tab.
on run {input, parameters}
set current_document_path to ""
tell application "Xcode"
set last_word_in_main_window to (word -1 of (get name of window 1))
if (last_word_in_main_window is "Edited") then
display notification "Please save the current document and try again"
-- eventually we could automatically save the document when this becomes annoying
else
set current_document to document 1 whose name ends with last_word_in_main_window
set current_document_path to path of current_document
end if
end tell
tell application "MacVim"
if (current_document_path is not "") then
activate
open current_document_path
end if
end tell
return input
end run