let user to draw rectangle to select an area - ios

Question

I'm new in Swift and I'm trying to let the user draw a rectangle (touching and dragging) to select an area of an image just like when cropping but I don't want to crop I just want to know the CGRect the user created.
So far I have a .xib with a UIImage inside and its ViewController. I want to draw above the image but every tutorial I found about drawing is about subclassing UIView, override drawRect and put that as the xib class.

Answer 1

I figured it out. I just created a uiview and change its frame depending on the touches events
let overlay = UIView()
var lastPoint = CGPointZero
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
overlay.layer.borderColor = UIColor.blackColor().CGColor
overlay.backgroundColor = UIColor.clearColor().colorWithAlphaComponent(0.5)
overlay.hidden = true
self.view.addSubview(overlay)
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
//Save original tap Point
if let touch = touches.first {
lastPoint = touch.locationInView(self.view)
}
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
//Get the current known point and redraw
if let touch = touches.first {
let currentPoint = touch.locationInView(view)
reDrawSelectionArea(lastPoint, toPoint: currentPoint)
}
}
func reDrawSelectionArea(fromPoint: CGPoint, toPoint: CGPoint) {
overlay.hidden = false
//Calculate rect from the original point and last known point
let rect = CGRectMake(min(fromPoint.x, toPoint.x),
min(fromPoint.y, toPoint.y),
fabs(fromPoint.x - toPoint.x),
fabs(fromPoint.y - toPoint.y));
overlay.frame = rect
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
overlay.hidden = true
//User has lift his finger, use the rect
applyFilterToSelectedArea(overlay.frame)
overlay.frame = CGRectZero //reset overlay for next tap
}