Question

I’m trying to do some progress indication for when trying to upload and download a file.

Been reading and looks like this is the method that I need to use.

- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite

I’d like to read more about how that function works (i.e when is it called etc), but can’t seem to find the reference documentation. I went to this URL but it does not say anything about that particular function.

https://developer.apple.com/library/mac/#documentation/Foundation/Reference/NSURLConnectionDelegate_Protocol/Reference/Reference.html%23//apple_ref/occ/intf/NSURLConnectionDelegate

Where can I read more about it?

Thank you,
Tee

Answer 1

NSURLConnection had an informal protocol for its delegate. That changed in iOS 5 (I think the same happened on OSX). They deprecated the methods declared in NSURLConnection and moved them into formal protocols NSURLConnectionDelegate and NSURLConnectionDataDelegate.

And now the fun part. They deprecated the methods, they even removed them from the NSURLConnection documentation but they did not document the new formal protocols.
Currently, only NSURLConnectionDelegate is documented. NSURLConnectionDataDelegate is not mentioned anywhere.

There are two ways how to find what the method does.

1. Look into the previous version of NSURLConnection docs (e.g. iOS 4.3). I would give you a link but I couldn’t find it online. Maybe you have the library downloaded in your XCode

2. Press cmd-shift-o in Xcode, type NSURLConnectionDataDelegate and press enter. You have found the header and the methods have a description there:

   connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:
   is called during an upload operation to provide
   progress feedback. Note that the values may
   change in unexpected ways if the request needs to
   be retransmitted.