custom encoder for Data - swift

Question

I got a series of data as bytes, I tried to encode it
let encoder = JSONEncoder()
encoder.dataEncodingStrategy = .deferredToData
let encodedData = try encoder.encode(data)
let data = encodedData.compactMap { $0 }
my data is looks like that:
[ 91,91,48, 44, 49, 57, 51, ..., 49, 44, 48, 93, 93]
It works, but the outcome is not what I expected (the numbers inside the data.element are different), then I tried to change the encoding strategy.
encoder64.dataEncodingStrategy = .base64
let data = encodedData.compactMap { $0 }
[91, 34, 65, 77, 72, ..., 65, 61, 61, 34, 93]
Then I have a different results, but still not is the what that I expected.
there is another custom encoding strategy, could you please give me some example of this custom strategy that I can test another forms to compare the results.
the example data that I expected is like :
[ 0, 193, 193, 193, 193, 72, 20, 193, ..., 255, 91, 0]
the 0 in the beginning and in the end is so important to me.
Thank you so much

Answer 1

The output is correct.
The JSONEncoder creates a JSON string from the data and compactMap maps each character to its UInt8 value
91 is [
91 is [
48 is 0
44 is ,
49 is 1
57 is 9
51 is 3
...
49 is 1
44 is ,
48 is 0
93 is ]
93 is ]
And consider the different representations: 91hex is 145dec