Progress for uploads not working on iOS

[shannah]

For multipart requests with large file uploads, iOS first buffers the body to disk before performing the request. This results in progress listeners reporting the progress of the initial writing the body to disk, but will just sit at 100% while the actual network request is created.

For iOS, we'll need to hook the progress listener into the NSNetworkConnection delegates' (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite callback as shown in this SO post

[javieranton-zz]

Hi shannah, I just pulled a request with a lib that does this (multipart, ios and android). just fyi

https://github.com/javieranton-zz/ProgressUploader