How to Select Range - FSCalendar in Swift?

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06-10-2024

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Selecting a Range of Dates with FSCalendar in Swift

Problem: You're working with a calendar in your Swift iOS app and need to let users select a range of dates, like a vacation period or booking timeframe. You're using the popular FSCalendar library, but finding it tricky to implement this functionality.

Solution: This article will guide you through selecting a range of dates with FSCalendar. We'll cover the core concepts and provide a practical code example to help you integrate this feature seamlessly into your app.

Understanding the Basics

FSCalendar, a powerful and customizable calendar component for iOS, provides a dedicated method for handling range selections. The key is to leverage the FSCalendarDelegate protocol, which allows you to intercept user interactions and manage your calendar's behavior.

Code Implementation

Let's illustrate this with a simple example:

import UIKit
import FSCalendar

class ViewController: UIViewController, FSCalendarDelegate, FSCalendarDataSource {
    @IBOutlet weak var calendar: FSCalendar!
    
    var selectedStartDate: Date?
    var selectedEndDate: Date?

    override func viewDidLoad() {
        super.viewDidLoad()
        calendar.delegate = self
        calendar.dataSource = self
    }

    // MARK: - FSCalendarDelegate

    func calendar(_ calendar: FSCalendar, didSelect date: Date, at monthPosition: FSCalendarMonthPosition) {
        // Check if start date is already selected
        if let startDate = selectedStartDate, startDate == date {
            // Deselect the start date and reset
            selectedStartDate = nil
            selectedEndDate = nil
            calendar.deselect(date) 
            return
        }

        // Handle first selection as start date
        if selectedStartDate == nil {
            selectedStartDate = date
            calendar.select(date)
        } else {
            // Handle second selection as end date
            selectedEndDate = date
            calendar.select(date)

            // Highlight the range between start and end dates
            calendar.select(dates: [Date]
                .dates(from: selectedStartDate!, to: selectedEndDate!)
                .filter { $0 != selectedStartDate && $0 != selectedEndDate }
            )
        }
    }

    func calendar(_ calendar: FSCalendar, didDeselect date: Date, at monthPosition: FSCalendarMonthPosition) {
        // Reset selections on deselect
        selectedStartDate = nil
        selectedEndDate = nil
    }
}

// Helper function to generate a range of dates
extension Array where Element == Date {
    static func dates(from startDate: Date, to endDate: Date) -> [Date] {
        var dates: [Date] = []
        var currentDate = startDate
        while currentDate <= endDate {
            dates.append(currentDate)
            currentDate = Calendar.current.date(byAdding: .day, value: 1, to: currentDate)!
        }
        return dates
    }
}

Explanation

1. Delegate and DataSource: We set the delegate and dataSource of the FSCalendar instance to our ViewController. This allows us to receive callbacks for user interactions.

2. didSelect Method: This method is triggered whenever a user selects a date on the calendar.

   • We first check if a start date is already selected. If so, we deselect the start date and reset the selections.
   • If no start date is selected, we store the current date as the selectedStartDate.
   • If a start date is already selected, we store the current date as the selectedEndDate.
   • Finally, we highlight the range between the start and end dates using calendar.select(dates:).

3. didDeselect Method: This method is triggered when a user deselects a date. We reset the selections to ensure proper behavior.

4. Helper Function: The dates(from:to:) function helps generate a range of dates between a start and end date.

Additional Tips

• Customization: FSCalendar allows you to customize the appearance of selected dates, including colors and backgrounds. You can modify these styles to enhance the visual feedback for range selections.
• Validation: You can implement additional logic to validate the selected range, ensuring it meets specific criteria for your application.
• Integration with Other Components: Use the selected range data to populate other UI elements, such as text fields or labels, to display the chosen time period.

Conclusion

By utilizing the FSCalendarDelegate protocol, you can effectively manage date range selections with FSCalendar. This empowers you to create intuitive and engaging user experiences for your iOS apps. Remember to tailor the implementation to your specific needs and leverage the customization options to create a visually appealing and functional calendar experience.