title: How to change background color of events array in FSCalendar swift 3?
body: <p>I'm having an 2arrays of dates and want to set different colors for particular event please help how to do this.</p>
  
  <p><strong>I'm trying to implement following code but its not working its returning nil no color effects no error nothing m stucked on this please help.</strong></p>
  
  <pre><code>import UIKit
  import FSCalendar
  
  class myCalendarViewController: UIViewController,FSCalendarDelegate,FSCalendarDataSource,FSCalendarDelegateAppearance {
  
      var presentdays = [String]()
      var absentdays = [String]()
  
  @IBOutlet weak var calendar: FSCalendar!
  
  fileprivate let gregorian: Calendar = Calendar(identifier: .gregorian)
  fileprivate lazy var dateFormatter1: DateFormatter = {
     let formatter = DateFormatter()
     formatter.dateFormat = "yyyy/MM/dd"
     return formatter
  }()
  
  override func viewDidLoad() {
        super.viewDidLoad()
  }
  
  func calendar(_ calendar: FSCalendar, appearance: FSCalendarAppearance,  titleDefaultColorFor date: Date) -&gt; UIColor? {
           presentdays = ["2017-06-03",
                          "2017-06-06",
                          "2017-06-12",
                          "2017-06-25"]
  
           absentdays = ["2017-06-10",
                         "2017-06-18",
                         "2017-06-15",
                         "2017-06-16"]
  
  let datestring2 : String = dateFormatter1.string(from:date)
  
  if presentdays.contains(datestring2)
  {
      return UIColor.green
  }
  else if absentdays.contains(datestring2)
  {
      return UIColor.red
  }
  else{
      return nil
  }
  
  }
     }
  </code></pre>