Apple Product Design Engineer interview questions

I've interview twice for this position on two separate teams at Apple, each with the same basic two-round structure: First is a one hour interview with the hiring manager or team lead, and second is a full-day onsite interview (and by full day I mean 6-8 hours all day) Where it's simply a constant onslaught of technical questions. In the second case between rounds there was a design project which required a presentation and accompanying analysis and documentation.