VSTKit, the Cocoa framework for hosting VST3 plug-ins, was recently updated to v0.6.

Changes since 0.5.5:

• Support for compiling with VST SDK 3.1.
• Add reverse lookup for Modules and Paths from uids.
• Add Notification to VSTAudioProcessor and VSTEditController for massive value changes.
• Add Notification to VSTEditController for message posting to the audio processor.
• New method in VSTEditorWindowController for subclasses to override for custom windows.
• New method in VSTHostClasses to use a custom host context.
• VSTPresetBrowserViewController searches for Application VST presets too now.
• VSTModule will only unload the bundle if no one else has a reference to the bundle.
• Workaround a bug with CFBundles when they are pointed to by symbolic links.
• Added more process context information to the VSTKit Test app audio engine.
• Added IUnitData support (Presets can now be saved for a unit or the complete state).
• Preset chunk data only loaded if requested.
• Add parameter finding interface to VSTEditor.
• Added toolbar to VSTKit Test app plugin windows (Cocoa editors only).
• Enable Key/Value Binding in VSTEditController.
• MIDI connection to Event Busses editable in VSTKit Test app.
• VSTPlugin class has now a dictionary to store arbitrary objects.
• Audio Device Setup for VSTKit Test app.
• Effect Chain Window for VSTKit Test App.
• Code changes for warning free compilation under Mac OS X 10.6.
• Added property cidString to VSTClassInfo to get the cid as NSString.
• Added method classInfoForCIDString: to VSTStore.
• Support dragging plugins out of VSTPluginBrowserViewController if the delegate permits it.
• Fix a bug in NSDataIBStream::seek when trying to seek to the end of the data.
• Added loading and saving of plugin chains in VSTKit Test App.
• Support for IComponentHandler2 in VSTEditController.
• Added parameter info cache in VSTEditController.
• Added performance measure code to VSTKit Test App.
• Added low prio threads for measuring to make speedstep non functional.