How can I change the opacity of the overlay behind UIPopoverPresentationController?

Question

I\'m using UIPopoverPresentationController to present popovers in an iOS app. I want to dim the background behind the popover when it comes up. How can I do thi

Answer 1

A drop-in non-intrusive solution: showing/hiding up an overlay view via UIPopoverPresentationControllerDelegate, like this: (in Swift 2.0)

class PopoverDelegate: NSObject, UIPopoverPresentationControllerDelegate {
    var overlay: UIView?

    dynamic func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
        return .None
    }

    dynamic func presentationController(presentationController: UIPresentationController, willPresentWithAdaptiveStyle style: UIModalPresentationStyle, transitionCoordinator: UIViewControllerTransitionCoordinator?) {
        // add a semi-transparent view to parent view when presenting the popover
        let parentView = presentationController.presentingViewController.view

        let overlay = UIView(frame: parentView.bounds)
        overlay.backgroundColor = UIColor(white: 0.0, alpha: 0.4)
        parentView.addSubview(overlay)

        let views: [String: UIView] = ["parentView": parentView, "overlay": overlay]

        parentView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[overlay]|", options: [], metrics: nil, views: views))
        parentView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[overlay]|", options: [], metrics: nil, views: views))

        overlay.alpha = 0.0

        transitionCoordinator?.animateAlongsideTransition({ _ in
            overlay.alpha = 1.0
        }, completion: nil)

        self.overlay = overlay
    }

    deinit {
        // remove the overlay with animation.
        // the delegate method popoverPresentationControllerDidDismissPopover(_:) is not called 
        // if the popover is dismissed programmatically, 
        // so the removal goes here.

        guard let overlay = overlay else {
            return
        }
        dispatch_async(dispatch_get_main_queue()) {
            UIView.animateWithDuration(0.2, animations: {
                overlay.alpha = 0.0
                }, completion: { _ in
                    overlay.removeFromSuperview()
            })
        }
    }

}

Then when a popver is about to be presented, set the delegate of UIPopoverPresentationController to an instance of PopoverDelegate, and you get a dimmed background behind the popover.