Here is a simple AppleScript for all of you... feel free to adapt and use it:
on run
set f to choose file
processTheFiles({f})
end run
on open theFiles
processTheFiles(theFiles)
end open
on processTheFiles(theFiles)
tell application "Image Events" to launch
repeat with f in theFiles
set thisFile to f as text
-- iPhone
scaleAndSave(f, thisFile, 29 * 1, "-iPhone-29")
scaleAndSave(f, thisFile, 29 * 2, "-iPhone-29@2x")
scaleAndSave(f, thisFile, 40 * 2, "-iPhone-40@2x")
scaleAndSave(f, thisFile, 57 * 1, "-iPhone-57")
scaleAndSave(f, thisFile, 57 * 2, "-iPhone-57@2x")
scaleAndSave(f, thisFile, 60 * 2, "-iPhone-60@2x")
-- iPad
scaleAndSave(f, thisFile, 29 * 1, "-iPad-29")
scaleAndSave(f, thisFile, 29 * 2, "-iPad-29@2x")
scaleAndSave(f, thisFile, 40 * 1, "-iPad-40")
scaleAndSave(f, thisFile, 40 * 2, "-iPad-40@2x")
scaleAndSave(f, thisFile, 50 * 1, "-iPad-50")
scaleAndSave(f, thisFile, 50 * 2, "-iPad-50@2x")
scaleAndSave(f, thisFile, 72 * 1, "-iPad-72")
scaleAndSave(f, thisFile, 72 * 2, "-iPad-72@2x")
scaleAndSave(f, thisFile, 76 * 1, "-iPad-76")
scaleAndSave(f, thisFile, 76 * 2, "-iPad-76@2x")
end repeat
tell application "Image Events" to quit
end processTheFiles
on scaleAndSave(aPath, aFile, aSize, aName)
set savePath to text 1 thru -5 of aFile & aName & text -4 thru -1 of aFile
tell application "Image Events"
set a to open aPath
scale a to size aSize
save a in savePath
end tell
delay 0.2
end scaleAndSave
Here is the same as a file... just download, save, double click and run: https://dl.dropboxusercontent.com/u/170740/AppIcon.applescript
I hope, this saves you some time...