How can I url-encode a text in UTF-8 notation?

Some times you may need convert text to utf-8 notation for web transmission, so you can pass “c%C3%A1spita” instead of “cáspita” (eg, if you are filling a form using curl).

These are the steps:
-Convert the input text to utf-8 (and grab its ASCII representation).
-Convert every unsafe byte to its hexadecimal equivalent.

This is only a method, but you can ellaborate yours one:

tell app "Smile" to escapeURL "cáspita --> "c%C3%A1spita"

Well, well… I’ll write some more code for the vanilla fans…

encodeTextUTF8("cáspita") --> "c%C3%A1spita"

to encodeTextUTF8(k)
	set someSafeChars to "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_."
	set f to {}
	repeat with i from 1 to (count k)
		set c to character i of k
		if c is not in someSafeChars then
			set tmp to text2utf8(c) --> transform to plain-ascii version of utf8
			set c to "%" & getHex(tmp's item 1)
			try --> may be two chars or not
				set c to c & "%" & getHex(tmp's item 2)
			end try
		end if
		set f's end to c
	end repeat
	return f as text
end encodeTextUTF8

to text2utf8(t)
	set theFile to "/tmp/utf8stuff" as POSIX file
	set f to (open for access theFile with write permission)
	set eof of f to 0
	write t to f as «class utf8»
	close access f
	read theFile
end text2utf8

to getHex(this_string)
	this_string as C string
		result * 512
	on error msg
		return text from character 22 of msg to character ((offset of "00» into type number" in msg) - 1) of msg
	end try
end getHex