Here is a typical example.
Code:
1391629189601 DeviceUsage LogStart {"SoftwareVersion":"3.4.4.13","DeviceId":"iOs-NTC-########-####-####-####-############-B-N-eReader","ModelNumber":"iPad3,4","TimeZone":"-28800000","AccountId":"<CENSORED>","SessionGUID":"<CENSORED>","ClientOSBuild":"6.1"}
1391629189663 CloudService sync_start {"connection":"wifi","category_id":"9 "}
1391629189668 Platform wake {}
1391629189696 CloudService sync_end {"category_id":"9 "}
1391629200862 CloudService download_start {"EAN":"9780062096753","connection":"WiFi"}
1391629202383 CloudService sync_start {"connection":"wifi","category_id":"9 "}
1391629203364 CloudService sync_end {"category_id":"9 "}
1391629204106 Library item_download {"EAN":"9780062096753"}
1391629207396 Library item_opened {"EAN":"9780062096753","sideloaded":"false","Size":"759"}
1391629207694 ePubReader product_opened {"font_size":"3","line_spacing":"medium","margin":"medium","justification":"true","doc_type":"ePub","theme":"0","font_type":"Georgia","orientation":"portrait","EAN":"9780062096753","current_position":"OEBPS/xhtml/Prologue.html#point(/1/4/6/1/1:385)"}
1391629208245 ePubReader page_turned {"method":"LRP","EAN":"9780062096753","destinationPage":"5.604769","pageDelta":"6.604769"}
1391629212153 ePubReader page_turned {"method":"tap","EAN":"9780062096753","destinationPage":"6.604769","pageDelta":"1.000000")
For sideloaded epubs, it sends the title of the book in the "EAN" field.
The IOS app doesn't upload as often as other clients, so it is harder to tell that the submission is happening
In ADDITION, the IOS apps sends "events" to "CRITTERCISM" and "FIKSU", both third party information collection services - I can't confirm this on other clients.