For Swift projects I tend to just default to Apache-2.0, as it's what Swift itself is licensed under (including the runtime, IIUC). Of course the choice is up to you.
I'm not a lawyer, I just know that GPLv3 is especially controversial because of that "parasitic" clause. IIRC, one of the main reasons Apple got invested in LLVM was because gcc moved to GPLv3, meaning they were stuck on the last GPLv2 release and didn't have a modern compiler (or at least that's the rumour). Same with the recent bash -> zsh switch.