Bottom Sheet small and large iOS

//
//  FeedbackBottomSheetVC.swift
//  BeFriends
//
//  Created by Ramesh Sanghar on 18/04/23.
//

import UIKit

class FeedbackBottomSheetVC: UIViewController {

    // 1
    lazy var containerView: UIView = {
        let view = UIView()
        view.backgroundColor = .white
        view.layer.cornerRadius = 16
        view.clipsToBounds = true
        return view
    }()

    // define lazy views
    lazy var titleLabel: UILabel = {
        let label = UILabel()
        label.textColor = .lightGray
        label.translatesAutoresizingMaskIntoConstraints = false
        label.text = "FEEDBACK"
        label.font = .systemFont(ofSize: 15, weight: .light)
        return label
    }()

    lazy var sendBtn: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("SEND", for: .normal)
        button.setTitleColor(StaticValues.TINT_COLOR, for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false
        button.addTarget(self, action: #selector(sendAction), for: .touchUpInside)
        return button
    }()

    lazy var lineView: UIView = {
        let line = UIView()
        line.translatesAutoresizingMaskIntoConstraints = false
        line.backgroundColor = StaticValues.TINT_COLOR
        return line
    }()

    // define lazy views
    lazy var feedBackTextView: UITextView = {
        let text = UITextView()
        text.textColor = .lightGray
        text.translatesAutoresizingMaskIntoConstraints = false
        text.text = "Your Text Here..."
        text.font = .systemFont(ofSize: 18, weight: .regular)
        return text
    }()

    // 2
    let maxDimmedAlpha: CGFloat = 0.6
    lazy var dimmedView: UIView = {
        let view = UIView()
        view.backgroundColor = .black
        view.alpha = maxDimmedAlpha
        return view
    }()

    let defaultHeight: CGFloat = 300
    let dismissibleHeight: CGFloat = 200
    let maximumContainerHeight: CGFloat = UIScreen.main.bounds.height - 64
    // keep updated with new height
    var currentContainerHeight: CGFloat = 300


    // 3. Dynamic container constraint
    var containerViewHeightConstraint: NSLayoutConstraint?
    var containerViewBottomConstraint: NSLayoutConstraint?

    var isLargeSizeEnabled = true

    override func viewDidLoad() {
        super.viewDidLoad()
        setupView()
        setupConstraints()
        setupPanGesture()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        animateShowDimmedView()
        animatePresentContainer()
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

        let touch = touches.first

        if touch?.view == dimmedView {
            animateDismissView()
        }
    }

    @objc private func sendAction() {

    }

    func setupView() {
        view.backgroundColor = .clear
    }

    @objc func handlePanGesture(gesture: UIPanGestureRecognizer) {
        let translation = gesture.translation(in: view)
        // Drag to top will be minus value and vice versa
      //  print("Pan gesture y offset: \(translation.y)")

        // Get drag direction
        let isDraggingDown = translation.y > 0
      //  print("Dragging direction: \(isDraggingDown ? "going down" : "going up")")

        // New height is based on value of dragging plus current container height
        let newHeight = currentContainerHeight - translation.y

        // Handle based on gesture state
        switch gesture.state {
        case .changed:
            // This state will occur when user is dragging
            if newHeight < maximumContainerHeight {
                // Keep updating the height constraint
                containerViewHeightConstraint?.constant = newHeight
                // refresh layout
                view.layoutIfNeeded()
            }
        case .ended:
            // This happens when user stop drag,
            // so we will get the last height of container
            // Condition 1: If new height is below min, dismiss controller
            if newHeight < dismissibleHeight {
                self.animateDismissView()
            }
            else if newHeight < defaultHeight {
                // Condition 2: If new height is below default, animate back to default
                animateContainerHeight(defaultHeight)
            }
            else if newHeight < maximumContainerHeight && isDraggingDown {
                // Condition 3: If new height is below max and going down, set to default height
                animateContainerHeight(defaultHeight)
            }
            else if newHeight > defaultHeight && !isDraggingDown {
                // Condition 4: If new height is below max and going up, set to max height at top
                animateContainerHeight(maximumContainerHeight)
            }
        default:
            break
        }
    }

    func animateContainerHeight(_ height: CGFloat) {
        UIView.animate(withDuration: 0.4) {
            // Update container height
            self.containerViewHeightConstraint?.constant = height
            // Call this to trigger refresh constraint
            self.view.layoutIfNeeded()
        }
        // Save current height
        currentContainerHeight = height
    }

    func setupPanGesture() {
        // add pan gesture recognizer to the view controller's view (the whole screen)
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.handlePanGesture(gesture:)))
        // change to false to immediately listen on gesture movement
        panGesture.delaysTouchesBegan = false
        panGesture.delaysTouchesEnded = false
        view.addGestureRecognizer(panGesture)
    }

    func animateShowDimmedView() {
        dimmedView.alpha = 0
        UIView.animate(withDuration: 0.4) {
            self.dimmedView.alpha = self.maxDimmedAlpha
        }
    }

    func animatePresentContainer() {
        // Update bottom constraint in animation block
        UIView.animate(withDuration: 0.3) {
            self.containerViewBottomConstraint?.constant = 0
            // Call this to trigger refresh constraint
            self.view.layoutIfNeeded()
        }
    }

    func animateDismissView() {
        // hide main container view by updating bottom constraint in animation block
        UIView.animate(withDuration: 0.3) {
            self.containerViewBottomConstraint?.constant = self.defaultHeight
            // call this to trigger refresh constraint
            self.view.layoutIfNeeded()
        }

        // hide blur view
        dimmedView.alpha = maxDimmedAlpha
        UIView.animate(withDuration: 0.4) {
            self.dimmedView.alpha = 0
        } completion: { _ in
            // once done, dismiss without animation
            self.dismiss(animated: false)
        }
    }

    func setupConstraints() {
        // 4. Add subviews
        view.addSubview(dimmedView)
        view.addSubview(containerView)
        dimmedView.translatesAutoresizingMaskIntoConstraints = false
        containerView.translatesAutoresizingMaskIntoConstraints = false

        containerView.addSubview(titleLabel)
        containerView.addSubview(sendBtn)
        containerView.addSubview(lineView)
        containerView.addSubview(feedBackTextView)

        // 5. Set static constraints
        NSLayoutConstraint.activate([
            // set dimmedView edges to superview
            dimmedView.topAnchor.constraint(equalTo: view.topAnchor),
            dimmedView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            dimmedView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            dimmedView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            // set container static constraint (trailing & leading)
            containerView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            containerView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            //containerView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: defaultHeight)
        ])

        // 6. Set container to default height
        containerViewHeightConstraint = containerView.heightAnchor.constraint(equalToConstant: defaultHeight)
        // 7. Set bottom constant to 0
        containerViewBottomConstraint = containerView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0)
        // Activate constraints
        containerViewHeightConstraint?.isActive = true
        containerViewBottomConstraint?.isActive = true

        NSLayoutConstraint.activate([
            // TitleLbl
            titleLabel.topAnchor.constraint(equalTo: containerView.topAnchor, constant: 12),
            titleLabel.heightAnchor.constraint(equalToConstant: 20),
            titleLabel.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: 10),
            titleLabel.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -10),
        ])

        NSLayoutConstraint.activate([
            // Send Btn
            sendBtn.centerYAnchor.constraint(equalTo: titleLabel.centerYAnchor),
            sendBtn.widthAnchor.constraint(equalToConstant: 80),
            sendBtn.heightAnchor.constraint(equalToConstant: 30),
            sendBtn.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -5),
        ])

        NSLayoutConstraint.activate([
            // Line View
            lineView.topAnchor.constraint(equalTo: sendBtn.bottomAnchor, constant: 5),
            lineView.heightAnchor.constraint(equalToConstant: 1),
            lineView.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -10),
            lineView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: 10)
        ])

        NSLayoutConstraint.activate([
            // Feedback Text View
            feedBackTextView.topAnchor.constraint(equalTo: lineView.bottomAnchor, constant: 18),
            feedBackTextView.bottomAnchor.constraint(equalTo: containerView.bottomAnchor, constant: -30),
            feedBackTextView.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -10),
            feedBackTextView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: 10)
        ])

    }
}



let vc = ShareBottomSheetVC()
        vc.modalPresentationStyle = .overCurrentContext
        // Keep animated value as false
        // Custom Modal presentation animation will be handled in VC itself
        self.present(vc, animated: false)