Skyscanner Mobile Developer - IOS interview questions

I applied online and after a week I received an email from the HR department saying that in order to progress with the application I had to do a coding challenge. It was to write an iOS app in Objective-C (no option of using Swift) where I had to implement the Skyscanner's search screen using their flight search APIs. They give you up to a week but it's a long task. Passing that stage I had a 1 hour phone interview with an HR employee about my previous experience and different soft skills related questions. The next round was a 1 hour video interview with a web engineer. Here he asked questions that had nothing to do with mobile development. Things like tell me the whole process that happens after entering a URL in the browser to seeing the website rendered. 🤨 I had 4.5/5 points in the coding challenge and I had the feeling both interviews went well (as I was able to reply to every question thanks to previous feedback on Glassdoor) but I got rejected. I asked for feedback on what went wrong as I was surprised but they didn't reply. There was supposed to be a fourth step. The worst is that the process takes really long, it's very time consuming and you are asked questions that have nothing to do with mobile development.