MyPresentationController

MyPresentationController.swift

import UIKit
import RxSwift

class MyPresentationController: UIPresentationController {
    
    /** To save keyboard animation duration. */
    private var _animationDuration : TimeInterval = 0.25
    
    /** To mimic the keyboard animation */
    private var _animationCurve = UIView.AnimationOptions.curveEaseOut
    
    private let disposeBag = DisposeBag()
    /** height of content */
    var controllerHeight: CGFloat = 200 + UIWindow.safeAreaInsetBottom
    
    lazy var dimmingView: UIView = {
        let view = UIView()
        if let frame = self.containerView?.bounds {
            view.frame = frame
        }
        view.backgroundColor = UIColor.black.withAlphaComponent(0.6)
        view.rx.tapGesture().when(.recognized)
            .subscribe(onNext: { [weak self](_) in
                self?.presentedViewController.dismiss(animated: true, completion: nil)
            }).disposed(by: disposeBag)
        return view
    }()
    
    override init(presentedViewController: UIViewController, presenting presentingViewController: UIViewController?) {
        super.init(presentedViewController: presentedViewController, presenting: presentingViewController)
    }
    
    override func presentationTransitionWillBegin() {
        containerView?.backgroundColor = .clear
        dimmingView.alpha = 0
        containerView?.addSubview(dimmingView)
        
        //Used UIViewAnimationOptionBeginFromCurrentState to minimize strange animations.
        UIView.animate(withDuration: _animationDuration, delay: 0,
                       options: UIView.AnimationOptions.beginFromCurrentState.union(_animationCurve),
                       animations: { () -> Void in
                        self.dimmingView.alpha = 1
        }, completion: nil)
    }
    
    override func dismissalTransitionWillBegin() {
        if let frame = self.containerView?.bounds {
            self.dimmingView.frame = frame
        }
        //Used UIViewAnimationOptionBeginFromCurrentState to minimize strange animations.
        UIView.animate(withDuration: _animationDuration, delay: 0,
                       options: UIView.AnimationOptions.beginFromCurrentState.union(_animationCurve),
                       animations: { () -> Void in
                        self.dimmingView.alpha = 0
        }, completion: nil)
    }
    
    override func dismissalTransitionDidEnd(_ completed: Bool) {
        self.dimmingView.removeFromSuperview()
    }
    
    override var frameOfPresentedViewInContainerView: CGRect {
        return CGRect(x: 0,
                      y: UIScreen.height - controllerHeight,
                      width: UIScreen.width,
                      height: controllerHeight)
    }
    
    override var presentedView : UIView? {
        let presentedView = super.presentedView

        // HACK: This is a workaround for the bug described in: http://openradar.appspot.com/18005149
        // UIKit changes the frame of the `presentedView` outside of our control. We can change that frame in
        // `containerViewWillLayoutSubviews()` but it's too late in the process - if we do that it's visible that
        // the frame changes without an animation during dismissal.
        presentedView?.frame = frameOfPresentedViewInContainerView

        return presentedView
    }
}