It's not ARC though. They use fancy threading mechanisms to avoid having to check on every access. Much faster.
"Swift uses Automatic Reference Counting (ARC) to track and manage your app’s memory usage."
https://docs.swift.org/swift-book/documentation/the-swift-pr...
alt Hacker News
"Swift uses Automatic Reference Counting (ARC) to track and manage your app’s memory usage."
https://docs.swift.org/swift-book/documentation/the-swift-pr...