Frame vs Bounds in iOS

Problem Explain the difference between frame and bounds on a UIView in iOS.

Be ready to discuss

• frame: the view's origin and size expressed in its superview's coordinate system, i.e. where the view sits inside its parent.
• bounds: the view's origin and size in its own coordinate system, with origin normally (0,0) unless the content is scrolled or the coordinate space is shifted.
• How applying a transform (rotation or scale) changes frame - it becomes the smallest axis-aligned rectangle enclosing the transformed view - while bounds stays unchanged.
• Why frame is undefined/unreliable for a non-identity transform, and why you should set bounds + center instead of frame in that case.
• Scroll views: UIScrollView scrolls by mutating bounds.origin (equivalently contentOffset), which is why subview frames don't change as you scroll.
• Setting bounds.size resizes the view around its center without moving it in its own coordinate space; setting frame.size resizes around the origin.
• Practical consequences for layout maths, hit testing, and converting points between views with convert(_:to:).