intersection point of rect and line problem (see: http://stackoverflow.com/questions/39735667/how-to-find-the-intersection-point-of-rect-and-a-line-starting-in-its-center)

RectangleProblem.swift

//: Playground - noun: a place where people can play

// Stackoverflow: http://stackoverflow.com/questions/39735667/how-to-find-the-intersection-point-of-rect-and-a-line-starting-in-its-center

import SpriteKit
import PlaygroundSupport

let pi = CGFloat(M_PI)
let angle = pi / 4 - 0.2
let rect = CGRect(x: 0, y: 0, width: 150, height: 150)

func point(forAngle angle: CGFloat, rect: CGRect) -> CGPoint {
  let t = tan(angle)
switch angle {
case 0..<(pi/2):
  //top right corner - works but only for square rects
  // t > 1 => top edge, t < 1 right edge
  let x = t > 1 ? rect.width + (1 - t) * rect.width / 2 : rect.width
  let y = t < 1 ? t * rect.height / 2 + rect.height / 2 : rect.height
  return CGPoint(x: x, y: y)
default:
  return CGPoint.zero
}
}

// Visualization Code
let view = SKView(frame: rect)
PlaygroundPage.current.liveView = view
let scene = SKScene(size: view.frame.size)
view.presentScene(scene)

let shape = SKShapeNode(rect: rect)
shape.fillColor = SKColor.clear
shape.strokeColor = SKColor.white
scene.addChild(shape)

let path = CGMutablePath()
path.move(to: CGPoint.zero)
path.addLine(to: CGPoint(x: rect.width, y: 0))
let line = SKShapeNode(path: path)
line.position = CGPoint(x: rect.midX, y: rect.midY)
line.strokeColor = SKColor.red
scene.addChild(line)
line.run(SKAction.rotate(toAngle: angle, duration: 3))

let dot = SKShapeNode(circleOfRadius: 4)
dot.strokeColor = SKColor.clear
dot.fillColor = SKColor.green
dot.position = point(forAngle: angle, rect: rect)
scene.addChild(dot)