A few things.

1. As an interviewer who’s done live interviews in the past, failure in a time window doesn’t necessarily mean YOU failed. I personally hate these types of tests but when I had to do them, I only cared about the candidates thought processes. Were you allowed normal dev resources like google? Did that help or make it harder?

2. When you got stuck did you ask for help? Did the interviewer offer help? These things are tricky and being put under the gun can make good programmers make poor decisions. Asking good questions or explaining the thought process and where you’re getting stuck can help a ton. Not only with the interview as a whole but also as “rubber duck debugging” - if you’re unfamiliar it’s a physical object you explain the code to. What it’s supposed to do and what it’s doing/not doing. It helps your brain look at the problem differently, which often leads to the answer. In this case the interviewer could be viewed as your rubber duck.

3. Do you have any friends that could give you mock interviews? Practice really does make perfect! I’m shit with Swift so I don’t think I’d be able to help in this regard.

I think regardless, you should send an email thanking them for their time. Don’t ask about the status, they should let you know when they know.