Question

Is it possible to use an NSURLConnection/NSURLRequest combination to send a PUT request to a server with a Content-Range header? By that I mean I want to resume an upload to the server which can accept a byte range in the request to resume the upload.

I see you can set an NSInputStream as the request body so I figured that I could subclass that and override the the open/seek functions and set the request header but it seems to call on undocumented selectors and break the implementation.

I’m sure I could do this with CFNetwork but it just seems like there must be a way to do it with the higher level APIs.

Any ideas on where to start?

EDIT:

To answer my own question, this is indeed possible after reading a blog [http://bjhomer.blogspot.com/2011/04/subclassing-nsinputstream.html] which details the undocumented callbacks which relate to CFStream. Once those are implemented I can call the following in the open callback to skip ahead:

CFReadStreamSetProperty((CFReadStreamRef)parentStream, kCFStreamPropertyFileCurrentOffset, (CFNumberRef)[NSNumber numberWithUnsignedLongLong:streamOffset]);

Thanks,
J

Answer 1

Like I posted in my comment, you can facilitate what you want without dropping down to the CoreFoundation level:

As NSInputStream inherits NSStream, it is possible to prepare the stream as follows:

NSNumber *streamOffset = [NSNumber numberWithUnsignedInteger:lastOffset];

[inputStream setProperty:streamOffset forKey: NSStreamFileCurrentOffsetKey];

(Assuming lastOffset is an NSUInteger representation of your last file offset in bytes and inputStream is the stream you want to set as the request’s HTTPBodyStream.)