BottomAlertViewController

BottomAlertViewController.swift

//
//  BottomAlertViewController.swift
//  
//
//  Created by MinKyungJun on 2022/04/26.
//

import Foundation
import UIKit
import SnapKit

class BottomAlertViewController: UIViewController {
    final class AlertView: UIView {
        
    }
    
    // MARK: Must Override
    open func setConstraint() { }
    open var alertHeight: CGFloat {
        get {
            return 0.0
        }
    }
    
    // MARK: Can Override
    open var backgrounColor: UIColor {
        get {
            return .clear
        }
    }
    
    // MARK: Public
    public var contentView: AlertView = AlertView()
    public func dispose(animated: Bool = true, completionHandler: (() -> Void)? = nil) {
       self.release(animated: animated, completionHandler: completionHandler)
    }
    
    // MARK: Fileprivate
    fileprivate var isKeyboardUprise: Bool = false
    fileprivate var topConstraint: Constraint?
    fileprivate var backgroundView = UIView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.modalPresentationStyle = .overFullScreen
        self.view.backgroundColor = self.backgrounColor
        
        /// 백그라운드 화면의 색상 지정과 UITapGestureRecognizer를 등록해준다.
        self.backgroundView.backgroundColor = self.backgrounColor
        let gesture = UITapGestureRecognizer(
            target: self, action: #selector(self.didTapBackground(_:))
        )
        self.backgroundView.addGestureRecognizer(gesture)
        self.backgroundView.isUserInteractionEnabled = true

        /// alertView가 추가되기 이전에 viewDidLoad에서 backgrounView를 먼저 추가한다.
        self.view.addSubview(self.backgroundView)
        self.backgroundView.snp.makeConstraints({
            $0.top.bottom.left.right.equalTo(self.view)
        })
        
        NotificationCenter.default.addObserver(
            self, 
            selector: #selector(self.willKeyboardShowUp(_:)), 
            name: UIResponder.keyboardWillShowNotification, 
            object: nil
        )
        NotificationCenter.default.addObserver(
            self, 
            selector: #selector(self.willKeyboardHideDown(_:)), 
            name: UIResponder.keyboardWillHideNotification, 
            object: nil
        )
    }
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        self.retain(animated: true)
    }
    @objc
    fileprivate func willKeyboardShowUp(_ notification: Notification) { 
        /// Keyboard의 높이는 notification의 userInfo 값 안에 담겨져서 들어온다.
        /// key값은 UIResponder.keyboardFrameEnduserInfoKey로 세팅하면 된다.
        guard let height = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }

        self.setAlertViewOffset(height.cgRectValue.height)
    }
    @objc
    fileprivate func willKeyboardHideDown(_ notification: Notification) { 
        self.setAlertViewOffset(0.0)
    }
    @objc
    fileprivate func didTapBackground(_ gesture: UITapGestureRecognizer) {
        /// 백그라운드 화면을 tap 했을 때 실행할 내용을 적어준다.
         guard !self.isKeyboardUprise else {
            self.isKeyboardUprise = false
            self.contentView.endEditing(true)
            return
        }
        
        self.release(animated: true)
    }
    fileprivate func setAlertViewOffset(_ offest: CGFloat) {
        /// 1. offset의 값이 0보다 크면 keyboard가 올라와 있다는 의미이다.
        self.isKeyboardUprise = offset > 0

        /// 2. offset의 값에 alertView의 높이를 더해야 topConstraint의 위치를 구할 수 있다.
        let yOffset = offset + self.alertHeight

        UIView.animate(withDuration: 0.5) { [weak self] in
            /// 3. topConstraint의 기준이 view의 바닥이기 때문에 
            /// offset + alertHeight 값을 마이너스 해줘야 view의 바닥으로부터
            /// 키보드 높이만큼 올라가는 효과를 볼 수 있다.
            self?.topConstraint?.layoutConstraints[0].constant = -yOffset
            self?.view.layoutIfNeeded()
        }
    }
    fileprivate func setAlertViewTapGesture(_ alertView: AlertView) {
        alertView.rx.tapGesture(configuration: { rec, delegate in
            /// TapGesture가 View의 객체로 전달되도록 허용
            rec.cancelsTouchesInView = false
            /// touchReceptionPolicy는 gestureRecognizer(_:shouldReceive:)와 같은 역할을 한다.
            delegate.touchReceptionPolicy = .custom { gesture, touch in
                /// touch한 view가 UITextField가 아닐 때에만
                /// view에 gesture를 전달하도록 한다.
                return !(touch.view is UITextField)
            }
        })
        .when(.recognized)
        .subscribe(onNext: { [weak self] recognizer in
            self?.isKeyboardUprise = false
            self?.contentView.endEditing(true)
        })
        .disposed(by: self.disposeBag)
    }
    fileprivate func retain(animated: Bool = true) {
        self.setConstraint()
        self.view.alpha = 0.0
        
        self.backgroundView.backgroundColor = self.backgrounColor
        self.view.addSubview(self.backgroundView)
        self.backgroundView.snp.makeConstraints({
            $0.top.bottom.left.right.equalTo(self.view)
        })
        
        let size = CGSize(width: 414.0, height: self.alertHeight)
        self.view.addSubview(self.contentView)
        self.contentView.backgroundColor = .white
        self.contentView.isUserInteractionEnabled = true
        self.contentView.frame.origin = CGPoint(x: 0, y: self.view.frame.height)
        self.contentView.frame.size = size
        
        self.contentView.snp.makeConstraints({
            self.topConstraint = $0.top.equalTo(self.view.snp.bottom).inset(size.height).constraint
            $0.size.equalTo(size)
            $0.centerX.equalTo(self.view)
        })
        
        self.topConstraint?.activate()
        
        self.contentView.roundCorners(corners: [.topLeft, .topRight], radius: 14)
        self.contentView.layoutIfNeeded()
        
        if animated {
            UIView.animated(withDuration: 0.5, animations: { [weak self] in
                self?.view.layoutIfNeeded()
            }, completion: { [weak self] _ in
                guard let self = self else { return }

                self.setAlertViewTapGesture(self.contentView)
            })
        } else {
            CATransaction.begin()
            CATransaction.setCompletionBlock { [weak self] in
                guard let self = self else { return }

                self.setAlertViewTapGesture(self.contentView)
            }
            self.view.layoutIfNeeded()
            CATransaction.commit()
        }
    }
    fileprivate func release(animated: Bool = true, completionHandler: (() -> Void)? = nil) {
        guard let topConstraint = self.topConstraint else { return }
        
        topConstraint.layoutConstraints[0].constant = 0
        
        let animatedHandler: () -> Void = { [weak self] in
            guard let self = self else { return }
            
            self.contentView.removeFromSuperview()
            self.topConstraint = nil
            
            self.dismiss(animated: false, completion: completionHandler)
        }
        
        if animated {
            UIView.animate(withDuration: 0.5, animations: { [weak self] in
                guard let self = self else { return }
                
                self.view.layoutIfNeeded()
                self.view.alpha = 0.0
            }, completion: {  _ in
                
                animatedHandler()
            })
        } else {
            CATransaction.begin()
            CATransaction.setCompletionBlock {
                animatedHandler()
            }
            self.view.layoutIfNeeded()
            self.view.alpha = 0.0
            CATransaction.commit()
        }
    }
    deinit {
        print("DEINIT BOTTOM ALERT VIEW CONTROLLER")
        
        NotificationCenter.default.removeObserver(
            self, 
            name: UIResponder.keyboardWillShowNotification, 
            object: nil
        )
        NotificationCenter.default.removeObserver(
            self, 
            name: UIResponder.keyboardWillHideNotification, 
            object: nil
        )
    }
}