Sorry do you mind if I ask a question about 暗くなっている? I've possibly mistakenly held both the definitions "is becoming, has become" for the phrase なっている. Certainly, now that I've see your answer, I see that when you say 暗くなっている aloud, it definitely sounds like it means "is becoming". Though is there ever a time where it means "has become"? — Chronopolis 3 hours ago

Sorry do you mind if I ask a question about 暗くなっている? I've possibly mistakenly held both the definitions "is becoming, has become" for the phrase なっている. Certainly, now that I've see your answer, I see that when you say 暗くなっている aloud, it definitely sounds like it means "is becoming". Though is there ever a time where it means "has become"? — Chronopolis 3 hours ago

@Chronopolis Maybe you could post a spin-off question about 暗くなっている. By the way, there are four basic meanings to 〜ている, not just two: progressive (進行中), resultative (結果残存), habitual (習慣), and experiential (経験). — snailboat ♦ 44 secs ago