swift drag and drop with collision - swift

Question

I'm new to Swift. I'm trying to figure out how to drag and drop and image onto a box and detect when the collision occurs. When I let gravity and animation act on the image it detects the collision. But when I drag the image to the box it doesn't detect it. I would appreciate any help! Thanks.
Here's the code I'm trying to use:
import UIKit
import AVFoundation
class Punc2ViewController: UIViewController, UICollisionBehaviorDelegate {
var player2:AVAudioPlayer = AVAudioPlayer()
var error : NSError? = nil
var location = CGPoint(x: 0, y: 0)
var animator: UIDynamicAnimator!
var gravity: UIGravityBehavior!
var collision: UICollisionBehavior!
#IBOutlet weak var period: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
period.center = CGPointMake(650, 100)
view.addSubview(period)
let barrier = UIView(frame: CGRect(x: 600, y: 200, width: 130, height: 20))
barrier.backgroundColor = UIColor.redColor()
view.addSubview(barrier)
animator = UIDynamicAnimator(referenceView: view)
//gravity = UIGravityBehavior(items: [period])
//animator.addBehavior(gravity)
collision = UICollisionBehavior(items: [period])
collision.collisionDelegate = self
// add a boundary that has the same frame as the barrier
collision.addBoundaryWithIdentifier("barrier", forPath: UIBezierPath(rect: barrier.frame))
collision.translatesReferenceBoundsIntoBoundary = true
animator.addBehavior(collision)
collision.action = {
}
}
func collisionBehavior(behavior: UICollisionBehavior!, beganContactForItem item: UIDynamicItem!, withBoundaryIdentifier identifier: NSCopying!, atPoint p: CGPoint) {
println("Boundary contact occurred - \(identifier)")
}
#IBAction func handlePan(recognizer:UIPanGestureRecognizer) {
let translation = recognizer.translationInView(self.view)
if let view = recognizer.view {
view.center = CGPoint(x:view.center.x + translation.x,
y:view.center.y + translation.y)
}
recognizer.setTranslation(CGPointZero, inView: self.view)
}
}

Answer 1

Use
if CGRectIntersectsRect(imageview.frame,imageview2.frame) {
//do something
}
It returns true if two objects(their frames) intersect