iOS Need help with UICalendarView

[iHorseHead]

Hello,
not really sure if it's the right place to ask, but does anyone have any idea how I could circle a date if it already has an event in it?
The UIKit doesn't have .circle() as SwiftUI does, but I was wondering if it's even possible with UIKit?
I just couldn't find a way to do it. Any advice or tips would be welcome.
I couldn't find anything from UICalendarView either.

Such circle would be enough:

Here's my current code:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        CalendarComponent()
    }
    //Dictionary to store events
    var events: [DateComponents:String] = [:]
    var eventLabel: UILabel!
    // Calendar Component
    func CalendarComponent() {
        let calendarView = UICalendarView()
        let gregorianCalendar = Calendar(identifier: .gregorian)
        calendarView.translatesAutoresizingMaskIntoConstraints = false
        calendarView.calendar = gregorianCalendar
        calendarView.locale = .current
        calendarView.fontDesign = .rounded
        view.addSubview(calendarView)
        // Date selection
        let dateSelection = UICalendarSelectionSingleDate(delegate: self)
        calendarView.selectionBehavior = dateSelection
       
        // Calendar Layout
       
        NSLayoutConstraint.activate([
            calendarView.leadingAnchor.constraint(equalTo:view.leadingAnchor,constant: 10),
            calendarView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -10),
            calendarView.heightAnchor.constraint(equalToConstant: 350),
            calendarView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
        ])
        // Event Label
       
        eventLabel = UILabel()
        eventLabel.translatesAutoresizingMaskIntoConstraints = false
        eventLabel.numberOfLines = 0
        eventLabel.textAlignment = .center
        view.addSubview(eventLabel)
       
        NSLayoutConstraint.activate([
            eventLabel.topAnchor.constraint(equalTo: calendarView.bottomAnchor, constant: 20),
            eventLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 10),
            eventLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -10)
        ])
    }
}

extension ViewController: UICalendarViewDelegate, UICalendarSelectionSingleDateDelegate {
    func calendarView(_ calendarView: UICalendarView, decorationFor dateComponents: DateComponents) -> UICalendarView.Decoration?
    {
        return nil
    }
   
   
        // Date Selection
    func dateSelection(_ selection: UICalendarSelectionSingleDate, didSelectDate dateComponents: DateComponents?) {
        // Check if a date was selected
        guard let dateComponents = dateComponents else {
            return
        }
       
        // Alert input
        let alertController = UIAlertController(title: "New Event", message: "Enter event details", preferredStyle: .alert)
       
        // Alert text field
        alertController.addTextField { textField in
            textField.placeholder = "Event Details"
        }
       
            // Save button for the event
        alertController.addAction(UIAlertAction(title: "Save", style: .default) { _ in
            // Get the event details from the text field
            let eventDetails = alertController.textFields?.first?.text ?? ""
           
            // Save the event details in the events dictionary
            self.events[dateComponents] = eventDetails
           
            // Print the events console
            print(self.events)
           
        })
       
        // Cancel button for the alert controller
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel))
       
        // Present the alert
        self.present(alertController, animated: true)
       
        // Update the event label
       
        if let eventDetails = events[dateComponents]{
            eventLabel.text = "Upcoming event: \(eventDetails)"
            eventLabel.textColor = UIColor.tintColor
        }
        else{
            eventLabel.text = "No upcoming events today"
            eventLabel.textColor = UIColor.black
        }
    }
   
}

 

[casperes1996]

The decorations for which you return nil might hold the key:

UICalendarView.Decoration | Apple Developer Documentation

A view that a calendar view displays for a specific date.

developer.apple.com