NSView Frames vs Bounds

• Both are NSRect properties expressing a view’s location and size.
• View's location and sized expressed in two ways:
  • Frame is in terms of superview's coordinate system.
  • Bounds is in terms of local coordinate system.
• Prior Misconception: Bounds size is always the same as Frame size. It’s easy to think this because updating a view’s frame scales its bounds accordingly.
• But actually... a view’s frames and bounds might be different from each other caused by:
  • Setting a view’s bounds directly does not scale its frame.
  • Scaling a view using scaleUnitSquareToSize: updates its bounds, but not its frame.
  • Rotating a view with boundsRotation updates its bounds, but not its frame.
• When to use frame?
  • When using a view, e.g., creating, positioning.
• When to use bounds?
  • When implementing a view, e.g., drawing, event handling.