ChunkInputStream is a subclass of NSInputStream that wraps read access to a certain byte-range (chunk) of a file.

Use case: upload a chunk of a file by constructing NSURLRequest with HTTPBodyStream.

let fileInputStream = NSInputStream(fileAtPath: "/tmp/readme")
let inputStream = ChunkInputStream(inputStream: fileInputStream)
inputStream.startPosition = 2097152
inputStream.readMax = 1048576

This creates an inputStream that gives access to the byte-range 2097152-3145727 of the file /tmp/readme.

See the included test project for a full example.

This is an adaption of BJ Homer's great example subclass HSCountingInputStream.