NSButton.BezelStyle.circular
A round button that can contain either a single character or an icon.
Declaration
case circularDiscussion
Use this button type to display either a single character:
Or a small icon.
Use system images such as SF Symbols for best results as they automatically scale to fit the button. Large images don’t clip when they display with this style. Instead, they shrink to fit the button’s bounds.
For design guidance, see Human Interface Guidelines > Buttons.