Subtract a CGRect from another

CGRect+Subract.swift

import CoreGraphics

public extension CGRect {

  func subtract(_ subtrahend: CGRect, edge: CGRectEdge) -> CGRect {
    guard intersects(subtrahend) else { return self }

    let intersectSize: CGSize = intersection(subtrahend).size

    let distance: CGFloat = (edge == .minXEdge || edge == .maxXEdge)
      ? intersectSize.width
      : intersectSize.height

    return divided(atDistance: distance, from: edge).remainder
  }

}