Download file from SharePoint

I'm using the REST APIs of SharePoint to query the files hosted inside a corporate user's Office 365 SharePoint site.

I have used OAuth to authenticate the user and authorize the the app, as described here: http://msdn.microsoft.com/en-us/library/azure/dn645542.aspx

I am able to successfully query the API with a GET request on:https://XXXXXXX.sharepoint.com/sites/xxxxx/xxxxx/myfoldername/_api/files(the request as the Authorization header set to 'Bearer ', as you'd expect.)

The above query gives me the following JSON result:

{"odata.metadata" = "https://xxxxxxxxx.sharepoint.com/sites/xxxxxxxxx/xxxxxxxxx/myfoldername/_api/$metadata#SP.ApiData.Files";    value =     (                 {            CreatedBy =             {                Id = 1;                Name = “Test”;                Puid = xxxxx;            };            ETag = “\”{hsdglksjfldkasnfldasknk},4\””;            Id = JKLBbiuuu908yYHhh89YBn9n9ynynYUN;            LastModifiedBy =             {                Id = 1;                Name = “XXXXX”;                Puid = XXXXXXXXXXX;            };            Name = "videofile.wmv";            Size = 56492358;            TimeCreated = "2013-09-23T05:16:44Z";            TimeLastModified = "2013-09-23T05:28:42Z";            Url = "https://xxxxxxxxx.sharepoint.com/sites/xxxxxxxxx/xxxxxxxxx/myfoldername/Shared Documents/videofile.wmv";"odata.editLink" = "Web/Lists(guid’9568472598-2c28-489BF2-a1ae-kfjdasfkjb)/files(‘jkbvasdjfbakfndasnMNBBAMnsaldfan)”;"odata.id" = "https://xxxxxxxxx.sharepoint.com/sites/xxxxxxxxx/xxxxxxxxx/myfoldername/_api/Web/Lists(guid’987795-gfkjhghs-ty42398yhfo’)/files('jkbvasdjfbakfndasnMNBBAMnsaldfan')";"odata.type" = "MS.FileServices.File";        })}

(Bear in mind the above is not actually JSON, but text output from a JSON parser)

In the result above, I get an array of files inside the value part. I have cut this array down to one item for illustrative purposes.

You'll see each item represents a file's meta data. There's a property called Url; I then use this to attempt to download the file. I create an HTTP request, append the Authorization header with Bearer <access_token>, however, the response is always an HTTP 401 UNAUTHORIZED.

Please note: the software I'm writing is actually in Objective-C using AFNetworking 2's AFHTTPRequestOperationManager.

Does anyone know how I can actually download the file? I have seen references to some property called 'contentUrl' in the docs, but this property is not supplied.

thanksKris