I trying to compress and decompress string using lzma

Decompress process goes without any errors, after that if I take compressed data and try to decompress it back, as it is, all good

But I need to save compressed date to file, so when app is running I can get string and decompress it at runtime, this is where problems begins. I get exactly string, that I got from compressed process before, but at decompress I got error that says “Decompression error: Error Domain=NSCocoaErrorDomain Code=5377 “(null)”

My compress process

var dataForCompress = try String(contentsOfFile: filepath)
let data = dataForCompress.data(using: .utf8)! as NSData
let compressedData = try data.compressed(using: .lzma)

After that I tried to decompress string by convert compressedData to string and decompress this string like that

var dataString = String(decoding: compressedData, as: UTF8.self)
let nsdata = dataString.data(using: .utf8)! as NSData
let uncompressedData = try nsdata.decompressed(using: .lzma) as Data
let theString = String(data: uncompressedData, encoding: .utf8)

At that point I got error

If I just do this
let uncompressedData = try compressedData.decompressed(using: .lzma) as Data
Uncompress compressed date straight forward, its decompressed without error

I think problem is somewhere at my process with get data from string, because size of the string I get when convert data to string is much more than size of compressed data itself