How To Create And Write UTF-16 Text File Using Applescript? - ios

Question

I'm writing an Applescript to parse an iOS Localization file (/en.lproj/Localizable.strings), translate the values and output the translation (/fr.lproj/Localizable.strings) to disk in UTF-16 (Unicode) encoding.
For some reason, the generated file has an extra space between every letter. After some digging, I found the cause of the problem in Learn AppleScript: The Comprehensive Guide to Scripting.
"If you accidently read a UTF-16 file
as MacRoman, the resulting value may
look at first glance like an ordinary
string, especially if it contains
English text. You'll quickly discover
that something is very wrong when you
try to use it, however: a common
symptom is that each visible character
in your "string" seems to have an
invisible character in front of it.
For example, reading a UTF-16 encoded
text file containing the phrase "Hello
World!" as a string produces a string
like " H e l l o W o r l d ! ", where
each " " is really an invisible ASCII
0 character."
So for example my English localization string file has:
"Yes" = "Yes";
And the generated French localization string file has:
" Y e s " = " O u i " ;
Here is my createFile method:
on createFile(fileFolder, fileName)
tell application "Finder"
if (exists file fileName of folder fileFolder) then
set the fileAccess to open for access file fileName of folder fileFolder with write permission
set eof of fileAccess to 0
write ((ASCII character 254) & (ASCII character 255)) to fileAccess starting at 0
--write «data rdatFEFF» to fileAccess starting at 0
close access the fileAccess
else
set the filePath to make new file at fileFolder with properties {name:fileName}
set the fileAccess to open for access file fileName of folder fileFolder with write permission
write ((ASCII character 254) & (ASCII character 255)) to fileAccess starting at 0
--write «data rdatFEFF» to fileAccess starting at 0
close access the fileAccess
end if
return file fileName of folder fileFolder as text
end tell
end createFile
And here is my writeFile method:
on writeFile(filePath, newLine)
tell application "Finder"
try
set targetFileAccess to open for access file filePath with write permission
write newLine to targetFileAccess as Unicode text starting at eof
close access the targetFileAccess
return true
on error
try
close access file filePath
end try
return false
end try
end tell
end writeFile
Any idea what I'm doing wrong?

Answer 1

Here's the handlers I use to read and write as UTF16. You don't need a separate "create file" handler. The write handler will create the file if it doesn't exist. Set the "appendText" variable to true or false. False means overwrite the file and true means add the new text to the end of the current text in the file. I hope this helps.
on writeTo_UTF16(targetFile, theText, appendText)
try
set targetFile to targetFile as text
set openFile to open for access file targetFile with write permission
if appendText is false then
set eof of openFile to 0
write (ASCII character 254) & (ASCII character 255) to openFile starting at eof -- UTF-16 BOM
else
tell application "Finder" to set fileExists to exists file targetFile
if fileExists is false then
set eof of openFile to 0
write (ASCII character 254) & (ASCII character 255) to openFile starting at eof -- UTF-16 BOM
end if
end if
write theText to openFile starting at eof as Unicode text
close access openFile
return true
on error theError
try
close access file targetFile
end try
return theError
end try
end writeTo_UTF16
on readFrom_UTF16(targetFile)
try
set targetFile to targetFile as text
targetFile as alias -- if file doesn't exist then you get an error
set openFile to open for access file targetFile
set theText to read openFile as Unicode text
close access openFile
return theText
on error
try
close access file targetFile
end try
return false
end try
end readFrom_UTF16

Answer 2

If you're getting actual spaces between every character, you've probably got the '(characters i thru j of someText) as string' anti-pattern in your code [1]. That will split a string into a list of characters, then coerce it back into a string with your current text item delimiter inserted between each character. The correct (i.e. fast and safe) way to get a sub-string is this: 'text i thru j of someText' (p179-181).
OTOH, if you are getting invisible characters between each character [2], then yes, that'll be an encoding issue, typically reading a UTF16-encoded file using MacRoman or other single-byte encoding. If your file has a valid Byte Order Mark then any Unicode-savvy text editor should read it using the correct encoding.
[1] p179 states that this idiom is unsafe, but forgets to provide a practical demonstration of the problems it causes. [3]
[2] IIRC the example on p501 was meant to use rectangle symbols to represent invisible characters, i.e. "⃞H⃞e⃞l⃞l⃞o" not " H e l l o", but didn't come out quite that way so might be misread as meaning visible spaces. [3]
[3] Feel free to submit errata to Apress.