Uber IOS Engineer interview questions

I was contacted by a recruiter on linked in. After a brief interview, she offered me two choices: 1) the usual recruitment process, involving a technical screening, an on-site Interview, and a decision 2) attend a mobile engineering hiring event at the end of the month, where I would do a longer on-site, but skip the phone screen. I went with the latter option. She then asked me a series of iOS questions, and scheduled me for one of the 3 dates of the mobile engineering recruitment event. The event was about 5 hours, and consisted of several 1 on 1 interviews. (Preparation materials were sent well in advanced). There was a behavioral interview, an iOS coding challenge, a data structures & algorithms whiteboard Interview, and iOS app architecture / design Interview. I found the DSA Interview to be the most challenging.