请帮助我升级到swift 3后,我在我的项目中使用了第三方FSCalender,它显示错误
func maximumDate(for calendar: FSCalendar!) -> Date! {
let date = Date()
let dayString: String = calendar.string(from: date, format: "dd")
let monthString: String = calendar.string(from: date, format: "MM")
let yearString: String = calendar.string(from: date, format: "yyyy")
return calendar.date(withYear: 2099, month: 12, day: 31)
}