ios - Detect collision of two UIView's in swift -

i have 2 uiviews on viewcontroller. added pangesture first view , when start moving view second view move towards first view. want detect event when these 2 views collides. here code.

@ibaction func dragfirstview(sender: uipangesturerecognizer) {          let translation = sender.translationinview(self.view)          dispatch_async(dispatch_get_main_queue()) { () -> void in             uiview.animatewithduration(2.5, delay: 0.0, options: uiviewanimationoptions.curveeaseout, animations: {                 self.secondview.frame = cgrectmake(sender.view!.center.x + translation.x, sender.view!.center.y + translation.y, self.secondview.frame.size.width, self.secondview.frame.size.height)                 }, completion: nil)         }          sender.view!.center = cgpoint(x: sender.view!.center.x + translation.x, y: sender.view!.center.y + translation.y)         sender.settranslation(cgpointzero, inview: self.view)     } 

what

if (cgrectintersectsrect(secondview.frame, sender.frame)) {         //     } 

cgrectintersectsrect(::) : returns whether 2 rectangles intersect.