[jaruche]

I totally agree, with your point that we should use more real life problems like you mention. The issue here is that this often requires a lot of preparation from the interviewer. You can't always share the code you are working on with a candidate. I would have to find something similar, maybe setup a backend, etc.

Would you ask this problem to be solved on the spot or let them try at home with the help of friends? Should I restrict time e.g. 2 hours to create a login screen for an iOS app. Or let them take as much time as needed?

I'm interested to know if I could scale this process. We have sometimes to hire batches of 6 to 10 engineers at the time for very different projects and that's when these code challenges seems attractive. Thoughts?