I first applied for an iOS Engineering job using the links on Mutual Mobile's site. I didn't hear anything at all for about two weeks, and assumed that they weren't interested, but then got a note from HR asking if I was available to talk to their Director of iOS Engineering. I chatted with him for about 45 minutes, which was thoroughly enjoyable, given his interesting background and the chance to ask him about it and about his experiences with Mutual Mobile. (He was, of course, asking me all about my experience at the same time.)
After that conversation, HR again contacted me and asked if I could come in for a panel interview. I turned up at their offices and spoke again with the Director, as well as several other technical people and the HR rep. This conversation went for about an hour, and ranged over my general programming experience, my managerial experience, and my iOS programming experience. It included a mix of conceptual and specific questions, with an apparent goal of getting a read both on the knowledge I already had and how quickly I could learn new things.
After this interview, I got an employment offer a few days later from a different person in HR. I had some concerns about a few aspects of it, talked back and forth through the issues, reached an agreeable outcome, and started with the company shortly thereafter.