EPAM Systems Senior IOS Developer interview questions

First interview was introductory as usual. Everything is normal, nothing can be wrong at this stage. The second stage was tech interview. The interviewer started asking about my experience, how I'd solve particular situations in an agile environment, estimation problems etc. Then tech questions started. Usually for an iOS developer we assess such sections like: the programming language(swift, objc & their specifics), multithreading(thread, gcd, operations), UIKit(responsder chain, lifecycle, autolayout) and optionally algorithmic problem solving. Here the interviewer asked questions about swift, but not in depth, like on the surface. I answered to all questions correctly, except a simple one which I didn't know. Further I was given a algorithmic problem and solved it at first try and written a one page app constructing its architecture, decomposing it to layers, with best practices. After all this, I was given a feedback like a middle iOS developer. Which shocked me. Because I answered all the questions and know my level. Know my level because I passed several senior position tech interviews before this and handled them with ease. The most shocking aspect was, the interviewer assessed my level for particular language features, like swift structure - middle, optionals - senior etc. Which is nonsense. You give an overall mark for language knowledge. So I'm very disappointed with EPAM recruitment process, which was easy, but at the same time irrelevant feedback.