iOSアプリ　カレンダーに予定を登録したい

スケジュール管理アプリを作っております。

実現したい事は、このカレンダーに登録した予定を表示したいのです。

現状としまして

タップしたセルが何年の何月何日なのかを取得する方法がわからない
日時からセルを特定する実装方法がイメージできない

です。
完成イメージはGoogleカレンダーのような感じです。
よろしくお願いします。

カレンダーのソースコードです。

ViewController.swift
1import UIKit
2
3class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
4
5    let dateManager = DateManager()
6    let daysPerWeek: Int = 8
7    let cellMargin: CGFloat = 2.0
8    var selectedDate = Date()
9    var today: Date!
10    let weekArray = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]
11
12    @IBOutlet weak var headerView: UIView!
13    @IBOutlet weak var headerTitle: UILabel!
14    @IBOutlet weak var headerPrevBtn: UIButton!
15    @IBOutlet weak var headerNextBtn: UIButton!
16    @IBOutlet weak var calendarCollectionView: UICollectionView!
17    
18    //MARK:- Override
19    //    --------------------------------------------------------------------------------
20    //    viewDidLoad()
21    //    --------------------------------------------------------------------------------
22    override func viewDidLoad() {
23        super.viewDidLoad()
24        
25        let dateFormater = DateFormatter()
26        dateFormater.locale = Locale(identifier: "ja_JP")
27        dateFormater.dateFormat = "yyyy/MM/dd"
28        let oneDay = "2018/12/16"
29        print(oneDay)
30        let castDate = dateFormater.date(from: oneDay)
31        print(castDate)
32        
33        cellSizeSet()
34        headerTitle.text = changeHeaderTitle(date: selectedDate)
35        
36        calendarCollectionView.delegate = self
37        calendarCollectionView.dataSource = self
38        calendarCollectionView.backgroundColor = UIColor.white
39    }
40    
41    //MARK:- Method
42    //    --------------------------------------------------------------------------------
43    //    changeHeaderTitle(date: Date) -> String
44    //    --------------------------------------------------------------------------------
45    func changeHeaderTitle(date: Date) -> String {
46        let formatter: DateFormatter = DateFormatter()
47        formatter.dateFormat = "yyyy年/M月"
48        let selectMonth = formatter.string(from: selectedDate)
49        return selectMonth
50    }
51    
52    func cellSizeSet() {
53        let numberOfMargin: CGFloat = 8.0
54        let width: CGFloat = (calendarCollectionView.frame.width - cellMargin * numberOfMargin) / CGFloat(daysPerWeek)
55        let height: CGFloat = width * 1.0
56        let layout = UICollectionViewFlowLayout()
57        layout.itemSize = CGSize(width: width, height: height)
58        calendarCollectionView.collectionViewLayout = layout
59    }
60    
61    //MARK:- Delegate
62    //    --------------------------------------------------------------------------------
63    //    numberOfSections(in collectionView: UICollectionView) -> Int
64    //    --------------------------------------------------------------------------------
65    func numberOfSections(in collectionView: UICollectionView) -> Int {
66        return 2
67    }
68    
69    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
70        if section == 0 {
71            return 7
72        } else {
73            return dateManager.daysAcquisition()
74        }
75    }
76    
77    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
78        let cell = calendarCollectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CalendarCell
79        //テキストカラー
80        if (indexPath.row % 7 == 0) {
81            cell.textLabel.textColor = UIColor.red
82        } else if (indexPath.row % 7 == 6) {
83            cell.textLabel.textColor = UIColor.blue
84        } else {
85            cell.textLabel.textColor = UIColor.gray
86        }
87        //テキスト配置
88        if indexPath.section == 0 {
89            cell.textLabel.text = weekArray[indexPath.row]
90        } else {
91            cell.textLabel.text = dateManager.conversionDateFormat(indexPath: indexPath)
92        }
93        
94        let selectedBGView = UIView(frame: cell.frame)
95        selectedBGView.backgroundColor = .blue
96        cell.selectedBackgroundView = selectedBGView
97        return cell
98    }
99    
100    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
101        print(indexPath)
102        print(indexPath.row)
103    }
104    
105    //MARK:- Action
106    //    --------------------------------------------------------------------------------
107    //    oPrevBtn(_ sender: Any)
108    //    --------------------------------------------------------------------------------
109    @IBAction func oPrevBtn(_ sender: Any) {
110        selectedDate = dateManager.prevMonth(date: selectedDate)
111        calendarCollectionView.reloadData()
112        headerTitle.text = changeHeaderTitle(date: selectedDate)
113    }
114    
115    @IBAction func oNextBtn(_ sender: Any) {
116        selectedDate = dateManager.nextMonth(date: selectedDate)
117        calendarCollectionView.reloadData()
118        headerTitle.text = changeHeaderTitle(date: selectedDate)
119    }
120}
121
122extension UIColor {
123    class func lightBlue() -> UIColor {
124        return UIColor(red: 92.0 / 255, green: 192.0 / 255, blue: 210.0 / 255, alpha: 1.0)
125    }
126    
127    class func lightRed() -> UIColor {
128        return UIColor(red: 195.0 / 255, green: 123.0 / 255, blue: 175.0 / 255, alpha: 1.0)
129    }
130}
131
132