Version 4.0 of AudioKit uses Swift 4 and is Xcode 9 ready. Version 4 is the culmination of many great new additions to AudioKit from a number of core team members, old and new. There were 929 files changed over 648 commits since V3.7.1.

• Awesome new (optional) syntax for connection nodes e.g. "mic >>> delay >>> reverb >>> mixer"
• New taps by Dave O'Neill: AKLazyTap, AKRenderTap, AKTimelineTap
• New sample accurate nodes from Audive, Inc.: AKClipPlayer, AKClipRecorder, AKClipMerger
• New sample player: AKSamplePlayer
• Sample accurate timing demonstrated in iOS example "MetronomeSamplerSync"
• Mike Gazzarusso's guitar processing nodes: AKDynaRageProcessor Tube Compressor and AKRhinoGuitarProcessor Amp Model
• Audio Unit hosting with Ryan Francesconi's AKAudioUnitManager class and examples for iOS and macOS
• All synthesizer bank nodes contain vibrato and pitch bend controls (instead of frequencyMultiplier and detuningOffset)
• Better handling of routes and backgrounding
• Offline rendering on latest operating systems (demonstrated in tests, more examples soon)
• Update MIDI Monitor example to send MIDI Sysex (example is now called "MIDIUtility")
• New iOS Drums example and two new drum playgrounds
• New macOS examples: RandomClips, Recorder
• AudioKitUI is now a separate framework and maybe omitted when you don't need audio plots
• New themes for playgrounds and playground widgets by Yaron Karasik
• New AKTableView UI element to display static waveforms or any single value plot, with an example playground demonstrating its use
• Many new tests (were up to 323 tests)
• Improved README and other Github niceties

And much more actually, its just a bit hard to remember everything.

PLUS: There is actually a lot more on the way. Instead of waiting on it all to be ready, we're going to be adding quite a few majorly cool enhancements over the next few releases.

Thank you to everyone who is involved with AudioKit. The core team is just amazing, and the users who create the new audio apps with our software, well, that's why we're doing this, so thank you as well.