Drop In Fetch with base64 string and application/octet-stream header does not work on iOS

[suparngp]

R/N: 0.68.5
rn-fetch-blob: 0.12.0

Using the Fetch polyfill does not work on iOS with a base64 string and application/octet-stream.

const Fetch = RNFetchBlob.polyfill.Fetch as any
const blobFetch = new Fetch({
  // enable this option so that the response data conversion handled automatically
  auto: true,
}).build()

The constructor in Fetch runs JSON.stringify on the body which wraps it in quotes.

https://github.com/joltup/rn-fetch-blob/blob/master/polyfill/Fetch.js#L52

Then RNFetchBlobRequestBuilder on line https://github.com/joltup/rn-fetch-blob/blob/master/ios/RNFetchBlobReqBuilder.m#L159 tries to create an NSData which returns nil.

This same logic also runs on Android.
https://github.com/joltup/rn-fetch-blob/blob/master/android/src/main/java/com/RNFetchBlob/RNFetchBlobBody.java#L174

But it succeeds. It seems like Base64.decode(rawBody, 0) is more forgiving than NSData initializer and ignores additional quotes around a string.