Bluebird.swift v3.0.0 Release Notes

Release Date: 2018-08-16 // over 3 years ago
    1. On iOS 10+ and macOS 10.12+ the locking mechanism for Promise is backed by os_unfair_lock bringing a significant performance improvement. On prior versions of iOS and macOS the locking mechanism falls back to a serial DispatchQueue
    2. Expose a new Lock class that hides the implementation detail of the underlying lock, preferring os_unfair_lock when available, and falling back to a serial DispatchQueue when it's not.