During the phone interview, I felt that C is a better language to solve the string problem than Swift and it was not a Swift language related question. I asked the interviewer if it's required to be solved it in Swift and he said no. I solved it and he agreed that it's the right approach too. Later to my surprise, they rejected stating the reason that "the candidate is not aligned with the tech stack and environment". As we all know, FAANG companies don't make a big fuss about the language as long as the problem is solved. Looks like people at Paypal give unnecessary importance to things like language. Good riddance!